


the observer effect

by MistressEast



Series: quantum entanglements [1]
Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Banter, Getting Together, Identity Porn, M/M, Texting, Wrong Number AU, and dont think i didn't notice gen isnt in many of minamis photos!, brief mention of blood and decomposition, don't hide author's style please please, homoerotic hot air balloon rides, html and i are not friends, i can't believe i typed bohr-chan with my own two hands, i love francois and ryusui so much guys, i noticed and im making it angsty, i worked so hard to format this, i'm very bad with timelines so if i got something majorly wrong sorry!!, if dr stone can shove Knowledge down our throats then so can i goddammit, ignore the fact that theyre apparently texting on iphones but senku cant see the emojis, kind of lol, some character names get proper spellings but most are spelled like they are in the subtitles so eh, the blue is easier on my eyes, this is technically pre-relationship but don't worry. we know what's up ;)
Language: English
Status: Completed
Published: 2020-01-01
Updated: 2020-01-24
Packaged: 2021-02-27 10:55:22
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 21,708
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22065874
Author URL: https://archiveofourown.org/users/MistressEast/pseuds/MistressEast
Summary: More than a year before the petrification incident, Gen gets a text from a stranger.
Relationships: Asagiri Gen/Ishigami Senkuu
Series: quantum entanglements [1]
Series URL: https://archiveofourown.org/series/1844311
Comments: 154
Kudos: 1973
Collections: Sengen Week 2019-2020, favourite drst fics





	1. Chapter 1

**Author's Note:**

> it's new year's day!
> 
> i spent longer formatting this fic than i did writing it i stg. technically, i wrote this for sengen week, but i didn't want to follow a specific theme. i've been wanting to do a wrong number au for this pairing for a while so i decided, in the spirit of sengen week, to just go for it.
> 
> i've tested this fic on my android phone, my apple ipad, and my windows laptop and it looks fine, so fingers crossed everyone can see it as it's meant to be seen. make sure you don't hide the author's style bc my knowledge of the html for this fic is so tenuous, any change will render the whole thing unreadable.
> 
> i'll be honest, these characters aren't easy to write. i tried to keep them as in-character as possible. senku is, of course, a know-it-all, but i always got the impression gen was very proficient with soft sciences and cultural studies. and we get like no info about his background in the series, so i'm just making it up lol.
> 
> hope you enjoy!!

Right after the stagehand signals five minutes, Gen feels his phone vibrate in his back pocket.

Unsure who would be texting him other than his manager, who’s waiting in the green room, Gen pulls it out quickly, unlocking the screen. It’s from an unknown number.

Bohr says I’m right.  
  


Followed by a link.

Eyebrows raised, Gen taps the link. After a second of buffering, his phone browser pulls up a page that Gen recognizes as some sort of scientific article about quantum physics. He catches sight of the terms _matter wave nature_ and _observer effect_ before his eyes glaze over and he switches back to the messaging app.

Normally, he’d just ignore the message and block the number, like he does when fans occasionally get a hold of his personal information, but something about the sheer confidence of the message intrigues him and before he can stop himself, he’s tapping out a response.

From what I can tell, this Bohr person is dead and can’t weigh in on any personal arguments. One of several mistakes you’ve made today ;)  
  


His phone buzzes with a response before he can even put it back in his pocket.

You know that’s not what I mean, old man. The observer effect and the uncertainty principle are different, period. I’m trying to help you study, so take this seriously.  
  


Shaking his head, Gen starts typing again. Clearly, he’s been accidentally contacted by some sort of science nerd and he really needs to cut that off at the pass.

I should have been clearer: you’ve got the wrong number.  
  


Again, the response comes quickly:

Don’t try that on me again. I’m not falling for it.  
  


In his periphery, Gen sees the stagehand signaling two minutes, but he keeps frowning down at his phone.

Don’t be so pushy. No one likes an aggressive guy, you know.  
  
Stop trying to distract me from the fact that you were wrong.  
  
What exactly was I wrong about?  
  
Do I really need to spell it out for you? Fine, fine. After you were so INSISTENT about Heisenberg’s work, I took the liberty of tracking down these materials for you so that you don’t make such an embarrassing mistake on your selection exam. No need to thank me.  
  


Gen can’t help but snort at the gall. Who talks like this? Other than him, that is.

“Asagiri-san,” the stagehand whispers loudly.

“Coming, coming,” Gen sings, powering his phone off and tucking it back in his pocket. Let his unaware friend talk to themselves for a while.

He’s still smiling as he parts the curtains with aplomb to begin his act.

* * *

When Gen checks his phone later, after letting himself into his empty apartment, still flushed with energy from a successful show, he’s tickled to find eight missed notifications.

Most of them are paragraphs of technical-sounding jargon that Gen can barely parse, interspersed with fond-sounding insults and links to increasingly esoteric articles.

Flopping down on his sofa, Gen responds:

That’s ~fascinating~ and all, but I was serious earlier. If you want your wayward student to pass his exam, you should try texting him instead, sensei.   
  


This time, Gen has time to run a hand over his tired eyes and consider going to bed before the reply comes.

Hang on, you’re not joking?  
  
Nope~ double-check the number.  
  


Another few minutes pass, during which Gen assumes his mystery texter is cross-referencing his contacts. Then--

I apologize for that.  
  


Gen snorts.

It’s okay~ it’s not every day I get mysterious, passionate texts about science.  
  
You didn’t have to let me just keep rambling.  
  
I tried to tell you, sensei.  
  
Yeah, I guess you did.  
  
Tsk tsk. You should trust people more.   
  
To be fair, my father has tried that on me before to get out of studying.  
  
To his own son? How cold~  
  


After hitting send, Gen realizes he just assumed his mystery texter was male and quickly amends:

*child  
  
No, son is correct.  
  
Well, you sound like quite the taskmaster, so I guess I can’t blame him. What is he studying for?  
  
Or not studying, as the case may be.  
  
He’s trying to get selected for a manned mission to the International Space Station.  
  


Gen raises his eyebrows, stretching out on the sofa.

And you’re helping him?  
  
He needs the help. He’s a physics professor, but if he can’t even tell the difference between the observer effect and the uncertainty principle, then he’ll never pass the preliminary selection.  
  
Of course, of course.  
  


Gen has almost no idea what those words mean.

You certainly know a lot. Are you a professor too?  
  
Fishing for information?  
  
Are you saying you don’t trust me?  
  
I don’t know you.  
  
I don’t know you either.  
  
Fine then. I’ll tell you what I do if you tell me what you do.  
  


Gen considers for a second, tapping a finger against his lips. Basic stranger danger insists he not divulge personal information to a complete stranger over text message, but there’s something oddly charming about his new texting buddy. What harm can a little polite conversation do?

(And it’s not like he has anyone else texting him.)

Deal. I’m a performer~  
  
A performer of what?  
  
Sorry~ can’t tell you that. I’m getting fairly well-known. If I tell you what I perform, you might be able to track me down and murder me.  
  
That’s fair. You do seem pretty irritating. I’m not sure I’d be able to help myself.  
  


Gen cackles, rolling over on his side.

How cruel!  
  
It’s better to be safe.  
  
Your turn, sensei.  
  
I’m a student.  
  


So not a sensei. The title still seems apt, somehow. Gen takes a second to change the unknown number’s contact name to _Sensei_ before responding:

What’s your major?  
  
I’m in high school.  
  


Gen’s eyes widen.

You’re not!!  
  
Unfortunately, I am.  
  
Seeeriously?? You must be very precocious for your age.  
  
Okay, I’m not twelve. Quantum mechanics and particle wave research are well within high school curriculum.  
  
But helping someone study for a space program selection exam surely isn’t.  
  
It’s really not that impressive.  
  
No need to be modest!! I’m your fan, sensei~  
  
Oh, great. The wrong number I texted and lectured about Niels Bohr is cheering me on.  
  
You’re definitely younger than me and I barely understood any of what you sent me earlier. Of course I’m impressed~  
  
Please, that was nothing. It’s actually very easy to understand once you know the basics.  
  


This guy wants to explain, Gen realizes. He smiles. It’s not like he had plans for the evening.

I’m afraid I wasn’t a very good science student, sensei. Is it really that easy to understand?  
  
Anyone can pick it up. All you have to know is the fundamentals of particle physics, and that’s easy stuff. So in 1925, a physicist named Erwin Schroedinger….  
  


Gen sticks one of the couch pillows under his head and settles in.

* * *

It shouldn’t become a habit. Any sane person would laugh the whole thing off and stop talking to the guy who accidentally texted them about Niels Bohr, but Gen is nothing if not experimental. Every notification from Sensei makes him giddy. It’s the same feeling he gets when he works a kink out of his act, or when a trick goes right for the first time.

It’s fun, in a way. Gen prides himself on being able to figure out how people tick, and a stranger he only communicates with via text is a unique challenge. He can’t help testing this guy, or being delighted when Sensei tests him right back.

From what he can tell, Sensei responds best to genuine-seeming curiosity and understated praise. He can pick out probing questions instantly and is uninterested in flattery, but he’s eager to educate and responds well to certain kinds of compliments. It doesn’t take Gen long to uncover Sensei’s iron-clad ego, incredibly advanced for someone his age and solid enough to rival even Gen’s, but it’s obvious that Sensei isn’t arrogant. Confident and audacious, sure, but he’s the first to admit when he doesn’t know something and seems honestly intrigued by Gen’s knowledge of psychology.

Chatting with Sensei quickly becomes Gen’s favorite distraction. Perhaps he shouldn’t be so eager to text someone several years younger, but it’s not like either Gen or Sensei have any desire to meet.

Frued was a hack, of course, but he was the first to act on the concept of innate desires in his practice.  
  


Gen types, trying to keep his restless hands busy as he waits for his editor to arrive at their meeting spot. A publisher finally showed interest in his first book and he needs to make sure the draft is perfect before he sends it off.

He was wrong about literally everything, though, and it’s unfortunate that he’s the face of modern psychology.  
  
Oh yeah, the Oedipus complex guy.  
  


Sensei goes through long periods of silence, but when he’s in a talkative mood, he responds very quickly.

Among other things. He pioneered psychoanalysis but his theories on the unconscious are all out of line. Did you know he popularized the concept of the libido?  
  
I didn’t. That’s a psychology thing?  
  
Of course! And it ruined the whole field of study for a long time. Almost everything he proposed has been disproven, but his work has pervaded the general public, so we’ll never get rid of it. You’ve heard of Id, Ego, and Super-Ego?  
  
In passing.  
  
As if the human mind can be so easily compartmentalized.  
  
It’s interesting to see you speak so scathingly about something.  
  
This is my wheelhouse, sensei~ it’s kind of fun to know more about something than you.  
  
Psychology isn’t something I need in my line of work.  
  
Don’t be so hasty. You never know when you might need to get in someone’s head.  
  
If I ever need to do that, I’ll just call you.  
  


Blinking down at his phone, Gen almost misses his editor sliding into the booth across from him.

Sorry sensei, my editor is here. Gtg!!  
  


And he puts his phone in his backpack and tries not to think about why he’s blushing.

When his meeting is over and he’s nearly bouncing with excitement, he checks his phone again to find one new message.

Editor? Are you a writer?  
  


Gen curses internally. He’d been so caught up in his thoughts he didn’t even notice the slip. That’s just a little more information than he intended to share. He types slowly, biting his lip:

In a manner of speaking.  
  


Sensei responds quickly.

I thought you were a performer.  
  
I wear many hats. In this economy, it pays to diversify.  
  
It’s nothing you’d be interested in, sensei. Trust me.  
  


The typing bubble pops up, ellipses rippling for a beat, then disappears. A moment passes before Sensei’s reply comes:

I’ll take your word for it. That’s pretty cool, though.  
  


Relieved, Gen smiles.

Thank you~ but don’t be too nice, sensei. I’ll get used to it~  
  


He almost adds a winky face but stops himself. A winky face is a big commitment. He needs to probe a little more to discover how Sensei feels about emojis before taking that step.

Noted. And I looked into that guy we were talking about earlier. Even with my limited knowledge of psychology, I can tell you’re right. He is a hack.  
  
Thank you!!  
  


* * *

I’m not saying that memetics isn’t a legitimate field of study.  
  
You’re just saying it’s beneath you.  
  
No, I’m saying it’s not as vital as other anthropological fields.  
  
What is anthropology if not the study of memes?  
  
Is that a joke?  
  
Me~? Joking~?  
  
Memetics in the modern day can’t be compared to the study of things like art trends or linguistic analysis. That’s just a fact.  
  
I disagree. It’s social language, sensei! Doesn’t sending a specific image to someone to denote a particular emotion ultimately serve the same purpose as hieroglyphics? In the 1700s it was common for painters to paint themselves posing in window frames. How is that not a meme?  
  
Art historians would disagree with you.  
  
Do you know any art historians?  
  
Do you?   
  
That’s beside the point.  
  
Why don’t you ask an art historian and get back to me.  
  
Why don’t you ask Neils Bohr.  
  
Maybe I will.  
  
  
  
Little gray box.  
  
Omg, are you texting me on a brick? You need an upgrade, sensei.  
  
It’s funny--you’re not the first person to tell me that today.  
  
Someone who does as much research as you needs a high-quality smartphone.  
  
Mine works just fine, thank you.  
  
Obviously not, if you can’t see half of my adorable and super relevant emojis.  
  
Somehow I think I’ll survive.  
  
  
  
I can see that one.  
  
:P  
  


* * *

Leeches? Seeeeriously??  
  
Yeah, some hospitals still keep them.  
  
Ewww!!! Why?  
  
Nobody believes they suck out bad blood or anything. They have a really specific purpose.  
  
Ensuring that I never set foot in a hospital ever again?  
  
Yeah, and doctors will sometimes use them after reattaching a body part. If it’s something small like a finger or toe and they act fast enough, severed pieces can be reattached without too much damage.  
  
Oh, that’s good to know.  
  
Skilled surgeons can reconnect arteries, which carry blood from the heart to the limbs, but veins, which do the opposite, are smaller and harder to work with. So what happens is that blood flow can be reestablished to the severed part, but only in one direction, and since the limbs they’re working with are usually really small, normal draining methods don’t always work.  
  
  
  
So, to keep the limb from swelling with blood that has no way to get out, doctors will use leeches. They’re small enough to only take a little blood and infection isn’t a huge worry in such a sterile environment.  
  
Does the patient just have to stick leeches on themselves periodically for the rest of their life?  
  
Nah, the veins will grow back on their own after a while.  
  
That’s pretty cool, sensei, but, no offense:   
  
If you’re lucky, you’ll never have to see it firsthand.  
  
Yeah, fingers crossed.  
  


* * *

No, Houdini didn’t go to the seances because he believed in ghosts.  
  
Then why would he go?  
  
To disprove the mediums!!  
  
Wasn’t he a magician?  
  
That doesn’t mean he didn’t value the truth! He worked hard on his illusions but he never claimed to have supernatural powers and he hated people who exploited the public with lies for money.  
  
You would have liked him, sensei. He was very methodical. He’d wait until he had definitive proof that the medium was faking and then he’d reveal himself dramatically and out them as a fraud.  
  
I can see why you like him.  
  
You can’t tell me you wouldn’t love to flip a table and tell off a fake medium.  
  
Fake medium...implying there are real mediums?  
  
Well~ who’s to say?  
  
Don’t tell me you believe in ghosts.  
  
Fine, I won’t tell you.  
  
Oh my god.  
  
You can’t prove there aren’t ghosts!!  
  
The burden of proof is yours, man. I can’t prove a negative.  
  
Have you ever seen a ghost?  
  
...no  
  
¯\\_(ツ)_/¯  
  
Not yet!  
  
Do you really believe in that stuff?  
  
I’m just open to the possibility. There are a lot of crazy things in the world. You should know that better than anyone, Mr. Science Man.  
  
Nothing exists in the world that can’t be explained with science.  
  
Maybe ghosts and things like that are just a science we haven’t figured out yet.  
  
Doubtful.  
  
Psychology is a legitimate science, right?  
  
A SOFT science, but yes.  
  
But we barely know how the human brain works right now, yet there’s no denying there are extensive mental machinations governing everything we do. Just because we don’t understand it, that doesn’t mean it’s not there.  
  
That’s different.  
  
For now~  
  
Psychology moves slowly because it’s the mind trying to understand itself, but most of it is ultimately testable. Theories involving ghosts or the afterlife, by their very definition, can never be tested.  
  
So I guess we’ll never know for sure!  
  
As someone who knows so much about human psychology, I would think you’d be quick to attribute supernatural phenomenon to faulty human perception and memory. Isn’t that more logical?  
  
Sure, most of it is, but who am I to dismiss thousands of years of witness testimony? What are the odds they’re all wrong or lying?  
  
High.  
  
But can you say 100%?  
  
You know what, yeah. 100%  
  
Bet.  
  
Bet?  
  
If I die, I’ll come back and give you some sort of proof.  
  
IF you die??  
  
So if you stop hearing from me and then your house gets possessed, that’s me~  
  
You have no way of knowing where I live.  
  
I assume I’ll attain some sort of cosmic knowledge when my soul merges with the universe or whatever. I’ll find you ;)  
  
How’s that for burden of proof?  
  
I can hardly wait.  
  


* * *

Being in the entertainment industry at his age is as much a curse as it is a blessing.

Gen has the means to live on his own and support himself, he’s following his ambitions much earlier than most of his peers, and he’s doing what he loves every day. It’s hard work, to be sure. He writes all his own material and invents his own tricks, which usually take hours of workshopping and testing just to be feasible, not to mention the additional hours spent mastering every little motion and diversion to ensure his acts go smoothly. But even with the late nights, frustrated practice sessions, and pounds of discarded material, he’s proud of how far he’s come.

His extensive knowledge of psychology helps him navigate the adult-dominated worlds of broadcast and publishing, but sometimes it’s not enough. When you get down to it, Gen is a kid, something people are eager to remind him of when he gets a little too confident.

He slams his front door with a loud bang and fists his hands in his hair, clutching tight enough to make his eyes water. “I’m a _fucking mindreader_ ,” he hisses to himself. “What were they expecting?”

It’s obvious to him now that the host of the talk show he was invited on didn’t put much stock in his abilities, so she was ill-prepared when he started reading her. But what was he supposed to do? He’ll pull his punches if he’s briefed beforehand, but otherwise he’s going to give it his all. It’s not his fault she has unresolved issues with her daughter and an unhealthy dependence on caffeine pills. But instead of handling it like a professional, she decided to mock her teenage guest live on air when he couldn’t even defend himself.

Gen hadn’t even checked his phone afterward, too furious and dreading the reaction on social media. His book is nearly ready for print and this is the _opposite_ of what he needs right now.

But he has to check in with his manager, who’s probably boiling with rage over the whole thing. So he pries stiff fingers out of his hair and reaches into his messenger bag, stalking into the living room.

His phone lights up with several texts and a missed call from his manager and he groans, but before he can respond, he catches sight of a notification from Sensei. Right, they’d been texting before Gen went onstage. He should tell Sensei he’s signing off for the night.

And that’s why you actually shouldn’t drink tea for a sore throat.  
  
That’s super cool, sensei~! But I have to go for tonight~! :)  
  


When he doesn’t hear back right away, he assumes Sensei has moved on. But then, halfway through an explanatory text to his manager, his phone buzzes.

Did something happen?  
  


Gen blinks.

What do you mean, sensei?  
  
You went quiet for a long time and now you’re saying you have to go. And you used two tildes in one text. So I was just wondering if something was wrong.  
  
Aww, are you trying to read me? I thought you didn’t like psychology.  
  
This has nothing to do with psychology, I just recognize your mannerisms.  
  
Are you trying to change the subject?  
  
Of course not~  
  
Nothing happened, sensei. But I appreciate the concern   
  
I don’t trust that little gray box, but if you don’t want to talk about it, fine.  
  


Gen makes a face at his phone. Sensei always thinks he knows everything, but when you get down to it, they’re both strangers, and Sensei is younger than him. He has no reason to go blabbing about his problems to a high school kid he’s never even met.

After a tense text exchange and a frustrating phone call with his manager, Gen flops down on his bed, not even bothering to change. The room is dim, only illuminated by the street light spilling in through the window, casting a sickly yellow glow across the walls. Gen cups a hand over his eyes, exhaustion weighing him down.

But he’s still humming, buzzing too much for sleep.

His phone vibrates beside him.

He gropes for it, uncovering his eyes and squinting at the glowing screen, wondering what else his manager wants to complain about.

Do me a favor and look outside.  
  


Gen rereads the text several times, trying to parse it.

Why?  
  
Just do it. Are you near a window?  
  
Yes.  
  
Humor me.  
  


Sighing, Gen levers himself up and shuffles over to the window. His bed is in the corner of the room under the windowsill so he doesn’t have to get up. He peers through the glass but doesn’t see anything spectacular.

Okay, what am I looking for?  
  
Can you see the sky?  
  


Gen’s unit is pretty high up, and he doesn’t live too far into the city, so he can see a good swath of sky over the roofs of the low-lying buildings in his neighborhood.

Yes?  
  
What do you see?  
  
A lot of black. A few stars. Why?  
  
Do you see a short row of stars with a really bright one at the end?  
  
Well, really bright is subjective in the city, but yes I can see Sirius from where I am.  
  
So you know what it’s called.  
  
I do horoscopes sometimes~ I can recognize the zodiac constellations and the major stars. You can’t see most of them in the city, but they’re up there.  
  
Of course you do horoscopes. Why am I not surprised.  
  
Is there a point to this, sensei? It’s late and I’m sleepy   
  
I’m getting there.  
  


Gen snorts and settles into a cross-legged position.

Sirius is the brightest star in the sky because it’s the closest star to earth relative to its luminosity. It would outshine our sun over 20 times. And it’s always been the brightest star, so people have been curious about it since the dawn of mankind.  
  


Gen stares up at the little star speck in the sea of flat black above him. Even with the light pollution, it’s visibly brighter than the other stars in Orion’s belt.

Since you’re into astrology, I’m sure you know stories about Sirius.  
  
Of course. Canis Major. The dog star. The Greeks called it Orion’s dog. Ancient Persians associated it with Tishtrya, a rain-maker. Chinese mythology calls it the star of the celestial wolf. Native Americans had references to it in their culture as well.  
  
Yeah, so it’s been important for a while.  
  
Thousands of years.  
  
Right. People have been charting its path for a long time. But in 1844, a German astronomer discovered that it had been deviating from its path since 1755. He theorized that an unseen mass was affecting the path Sirius had been on for thousands and thousands of years.  
  
I see.  
  
It wasn’t until 1862 that researches found Sirius B, a white dwarf in Sirius’s shadow. White dwarfs are dying stars with low-to-medium mass. So this massive, ancient star was being affected by the gravity of a tiny, dying star that we didn’t even know about.  
  


Gen props one elbow on the window sill and leans his cheek on his hand, peering up at the little twinkle of Sirius in the distance, considering Sensei’s words. It’s interesting, but he can’t figure out why Sensei is telling him this now.

And you’re telling me all this because…?  
  
I just thought it was interesting.  
  
How things can change. Even our perceptions of things.  
  


Blinking, Gen rereads the message several times. Is...is Sensei trying to encourage him? Unbidden, a smile curls the corners of his mouth.

I guess you’re right, sensei~ you never know what’s gonna come along and change your path. A tiny, dying star, or a bad day.  
  
Or a wrong number.  
  


It takes a second for Sensei to respond.

Don’t get sentimental on me. I didn’t mean anything by it.  
  
I know, I know~ that would be way too sweet for someone like you.  
  


Gen glances back up at the sky, still smiling softly, and can’t help imagining Sensei, somewhere out there, looking up at the same little glowing dot.

So I won’t say thank you.  
  
Good. I’ll talk to you later.  
  
Goodnight, sensei.  
  


* * *

No.  
  
Just a hard no? Surely there’s room for debate.  
  
Within our lifetime, A.I. will not reach the point of true autonomy, so, no, consensual sex with a robot isn’t possible.  
  
I’m realizing that I forgot you’re a high schooler and I shouldn’t be discussing sex with you in any capacity.  
  
I’m not a child.  
  
You’re literally a child!! By definition!!  
  
Fine, we don’t have to talk about it, but I’m only interested in the scientific morality of the whole thing.  
  
Sex with robots or sex in general?  
  
Sex with robots.  
  
If A.I. can’t be fully autonomous, then does it matter that it’s not consensual?  
  
Omg, what’s wrong with me?? Don’t answer that!! This conversation is cancelled.  
  
You sure? You seem interested.  
  
I don’t really want to get into morality with you anyway, sensei. I get the feeling you and I won’t agree about the entire school of philosophy.  
  
Why? I think philosophy is important.  
  
But?  
  
But it bores me.  
  
There we go.  
  
It’s all talk and speculation. There’s nothing in philosophy that can be tested.  
  
And I know you hate that.  
  
The philosophers can sit in their ivory towers and talk themselves hoarse. I’d prefer to be on the ground actually figuring things out.  
  
Of course you would, sensei~ that’s what makes you so charming~  
  
I can sense your sarcasm.  
  
Me~? Sarcastic~? Never~!  
  
Anyway, I never said that people weren’t going to have sex with robots regardless, but without complete autonomy, the entire question of consent is moot.  
  
  
  


* * *

What do you MEAN you’ve never seen Alien???  
  
Do you want me to apologize??  
  
Do you have a rabb.it account? Make one. Now.  
  


* * *

I’m waiting for this centrifuge to finish spinning. What’s up?  
  
I’m rearranging my apartment.  
  
Oh?  
  
The feng-shui was really off. It was blocking all my chakras and I couldn’t stand it.  
  
Oh.  
  
JK!! I don’t really believe in that stuff.  
  
Ghosts are a maybe but Chinese spirituality is a definite no?  
  
For me at least. I’m just waiting for a phone call and needed to do something. I’m regretting it now though. I’m tired and sweaty but everything’s in the way so I have to finish :(  
  
Do you live alone?  
  
I’m a working professional, sensei~! I pay alllll my own bills~  
  
How old are you?  
  
Nosy!!  
  
Sorry, I just didn’t think you were that much older than me.  
  
I’m not, but I’m not in high school.  
  
College?  
  
I went right into the workforce. In a manner of speaking.  
  
I see.  
  
Are you planning to go to college?  
  
Yeah. I’ve already got scholarship offers.  
  
Seeeeriously?? That’s great!! Where do you want to go?  
  
Nosy.  
  
Sorry~! I got excited.  
  
Why didn’t you go to college? You’re perfectly intelligent.  
  
Wow, high praise from the boy genius himself  but the truth is I already knew what I wanted to do with my life. I can do my own research and my brand of entertainment requires more hands-on experience than I’d be able to get in a classroom. I didn’t see any point in delaying my start for several years just to pay money to learn things I can learn on my own.  
  
That makes sense. And you’ve clearly had some success.  
  
You could say that~ what do you want to make of yourself, sensei?  
  
I’m going to space.  
  
  
  
As soon as possible. I’m really only planning to go to college for networking purposes. Getting on a manned space mission requires knowing the right people.  
  
Oh, I know alllll about networking~ you’ll have to do something about that abrasiveness of yours, sensei.  
  
What abrasiveness?  
  
Not everyone likes a know-it-all.  
  
What about you?  
  
Well, clearly I don’t mind, since I’ve been texting you for a year now.  
  
Oh, it has been a year, hasn’t it?  
  
Sorry, I don’t remember the exact day :(  
  
February 3rd.  
  
Wow.  
  
I have good numerical recall.  
  
Clearly. I’m touched you bothered to file our anniversary in your enormous brain.  
  
Don’t be. It’s not every day I misread my dad’s new number and text a complete stranger about Niels Bohr.  
  
Well, for what it’s worth, I’m grateful.  
  
For what?  
  
For Bohr-chan of course! He advanced the study of quantum physics significantly!!  
  
Right. Thanks, Bohr.  
  
Thank you, Bohr-chan~!  
  


* * *

Gen catches segments of the shuttle launch broadcast on his phone during breaks from rehearsal. He has a big show coming up, so he can’t afford to take a day off, but he’s determined to watch because he’s positive Sensei will want to talk about it later.

The commentators talk about a lot of stuff Gen doesn’t really understand, but he gets the gist of it, and he manages to catch the take-off livestream. He texts Sensei right afterward.

That’ll be you someday!  
  


Accompanied by a screenshot from the launch. But then he has to return to rehearsal, so he powers his phone off and slides his gloves on.

A few hours later, on the train home, Gen checks his phone and is surprised to see no response from Sensei. He shrugs it off. It’s not like they’re in constant contact, after all. Sensei has his own life.

So he doesn’t think about it that evening, or the next morning when his phone is still quiet. By the end of that day, however, Gen can’t help feeling a little concerned. He would have sworn Sensei would be all over the shuttle launch, and he certainly isn’t shy about texting Gen when he’s excited about random scientific minutiae. So why the radio silence now?

He decides he’ll give it another day. He’s pretty busy himself, after all: preparing for his show, writing his next book, fielding interview requests, etc. After his first book took off, his career really accelerated, but he doesn’t have time to rest. The entertainment industry is always moving and he can’t afford to be left behind.

So he puts his phone away and opens his laptop to respond to some emails.

Another day turns into two, into three, four--then a week has gone by with no word from Sensei. Gen tries not to feel hurt. It’s not like this is the longest they’ve gone without speaking to each other, but he’d been _so_ sure Sensei would want to gush about the shuttle, and he’d been looking forward to sharing that excitement with him for reasons he doesn’t really want to examine.

 _Sensei is a student_ , Gen rationalizes, sitting on his bed, knees to his chest, staring at his dark phone on the duvet in front of him. _He probably just got busy with school_. 

The sun is mostly gone, nothing but a thin haze of orange on the horizon, but his room is lit by strands of string lights crisscrossing the walls haphazardly, a decision he made when he rearranged his apartment a while back. He kept the bed by the window, though, and every time he looks outside at night, he finds Sirius in the sky, recalling Sesnsei’s dry explanation so many weeks ago. It’s comforting in a way he can’t explain.

Now, he glances out the window, at the darkness overtaking the sky, and a thought occurs to him.

Sensei, can you see the ISS in the sky?  
  


He vaguely recalls hearing something about the ISS looking like a star from earth but he can’t remember the details. Could something so comparatively small really be visible from the surface?

After a whole week of nothing, Gen isn’t really expecting a response, so when his phone vibrates a minute later, he jumps.

Yes, but not for very long.  
  
What do you mean?  
  
Due to the way it’s orbiting earth, when it is visible, it looks like it’s moving very fast. It moves from horizon to horizon very quickly, so there’s not much to look at.  
  
Seeeriously? Can you see it from Japan?  
  
Not tonight, and probably not from the city. In the suburbs, maybe  
  
Not tonight? Did you look it up?  
  
I know the schedule.  
  


Gen can’t quite put his finger on it, but something seems off about Sensei tonight. Usually, he’d be chomping at the bit to explain the ISS’s orbit in excruciating detail, but he’s being shorter than usual. It’s hard to get a read on someone who’s not physically in front of him, but Gen’s been talking to Sensei long enough that he’s pretty sure he can tell when something’s up.

That being said, what can he even do about it? It’s not his business, not really. But when he factors in Sensei’s week-long absence, he just can’t shake the concern.

Fuck it, he thinks.

Is something wrong, sensei?  
  


He tosses the phone to the other side of the bed and glares out the window. This is stupid. He shouldn’t feel this nervous. Sensei didn’t hesitate prying into his personal life that one time, did he? They’re friends, in a weird way, and don’t friends ask about each other?

All rationalizations aside, he grits his teeth when his phone buzzes a minute later.

No. Sorry I disappeared for a week.  
  


Nothing, predictably. Sensei isn’t the type to be open with his feelings, Gen knows that much for sure. But something is obviously bothering him. Should Gen push it or let it go?

Yeah I was really lonely   
  
I thought you’d want to talk about the shuttle launch. I made sure to watch it just for you~  
  
I caught bits of it.  
  
Pretty cool, huh~?  
  
Of course.  
  


God, this is like pulling teeth. Gen pushes his hair behind his ear and tries again.

Didn’t you say your father was studying to go to space? How is that going?  
  
Pretty well.  
  
That’s great!! Maybe you two will be able to go together!  
  
Maybe.  
  


Gen pouts. If Sensei really doesn’t want to talk, he could just not respond. But then, since he’s still responding, as stilted as the conversation is, that probably means he does want to talk to someone but he doesn’t feel like getting into his personal problems. With that in mind, Gen starts typing.

You know, there’s a lot of interesting psychology associated with space travel.  
  
I bet.  
  
It’s hard to study, since the sample size of people who have actually been to space is so small, but it’s important to understand the effects space travel has on the human brain.  
  
Not just isolation studies either! We already know that isolation is dangerous for humans, but even when groups are in space together, problems can occur.  
  
Infighting?  
  
Sometimes, but what happens more often is that people start closing themselves off. It’s literally called psychological closing, and it can happen in several ways. After a while, groups on orbit will sometimes communicate less with mission control. They’ll basically close ranks on their group and develop a very exclusive attachment to each other, shutting out those that they don’t perceive as sharing their experiences. It’s usually just a response to group stress and works itself out after a while.  
  
I see.  
  
But psychological closing can happen to individuals too. Astronauts can sometimes self-isolate and stop communicating effectively. It’s easy to understand why. I can’t imagine a more stressful job   
  
Once you’re up there, one member of your group autonomizing can be a big problem, so there are measures in place to encourage team unity! Astronaut teams are encouraged to celebrate birthdays and holidays together and make calls to mission control as a group, as well as contact loved ones as much as possible.  
  
Are you trying to tell me something?  
  
Oh, I could never presume to tell YOU anything, sensei~! I just thought it was interesting. The fact that humans need to be social is so well-established that they have rules to make sure it happens in space~ how cool is that~?  
  
It just seems inconvenient.  
  
Even so, you can’t get around it. NASA agrees with me. You can’t go to space if you’re anti-social. The personality tests will flag you.  
  
I guess that makes sense.  
  
So you might want to rethink your ambitions, sensei.  
  
Excuse me?  
  
Someone who cuts off communication when stressed and evades questions about their well-being doesn’t seem like a good match for spaceflight in my humble opinion.  
  


Sensei’s text bubble pops up and disappears a few times. Gen watches it, chewing his bottom lip.

Good thing no one asked your opinion, then.  
  
¯\\_(ツ)_/¯  
  
Anyway, you’re being a hypocrite.  
  
Oh, I’m so sowwy about that, sensei! I’ll do better next time~!!  
  
You know, you’re really annoying sometimes.  
  
We have that in common.  
  
For the record, I am not anti-social.  
  
Have you spoken to your irl friends about your problem?  
  
There’s no problem.  
  
Okay, sensei~ I believe you~  
  
But just in case you ever do have a problem, I promise I’ll only judge you a little bit.  
  
There’s no problem.  
  
But.  
  
I suppose I was in need of a bit of a distraction.  
  
Well, I’m nothing if not distracting. It’s kind of my specialty.  
  
So, I guess I should say thanks.  
  
For what~?  
  
For Niels Bohr, of course.  
  
Right! Thanks, Bohr-chan!  
  
Thanks.  
  


Gen huffs out a laugh and turns his gaze back to the window. The stars are finally starting to blink awake in the night sky and Gen tilts his head, imagining a little streak of light rocketing across the horizon somewhere on earth.

* * *

Omg, I’m so tired!!!  
  
What are you doing up this late?  
  
What are YOU doing up this late??  
  
Working.  
  
Good little students should be in bed~  
  
I’m not interested in being a good student and you didn’t answer the question.  
  
If you must know, I was working too.  
  
Right, your mysterious job you don’t want me to know about.  
  
Exactly~ though I kind of wish I could tell you, because I have a LOT to complain about.  
  
You manage to complain just fine while being secretive.  
  
Noooo, you have no idea how lucky you are. I could be complaining way more.  
  
I guess there are things I wish I could be more specific about.  
  
I’ll listen to anything you want to say, sensei.  
  
So you can put it in your notes and use it to try and read my mind later? No thank you.  
  
How mean!! I don’t need notes to read your mind.  
  
That just makes me want to tell you even less.  
  
  
  
Are you really up working?  
  
I’ve got some chemicals heating and I misjudged the time and can’t leave.  
  
Aww. How much longer will it take?  
  
It’s hard to say. An hour?  
  
Seeeeriously??? To heat up some chemicals??  
  
They’re volatile. I can’t rush it.  
  
Want me to stay up with you?  
  
You don’t have to do that.  
  
It’s fine~ do you have your laptop? We could watch something.  
  
I do.  
  
I’m serious. You said you were tired so you should go to bed.  
  
But I’d rather stay up with you, sensei~  
  
Why?  
  
What do you mean why? I like talking to you. Why do you think we’ve been texting for over a year?  
  
Or could it be  you don’t like talking to me??  
  
No  
  
I mean, no, I like talking to you  
  
Good~!   
  
What do you want to watch?  
  
Whatever you want.  
  


* * *

Gen doesn’t give the future of their arrangement much thought. Whatever happens will happen, he figures. He kind of wants to meet Sensei some day, but he’s not in a rush, and he can’t imagine Sensei is too invested in meeting the stranger he texted accidentally and just kept talking to for some reason. What they’ve got works for them, and that’s all that matters.

Maybe they’ll meet up someday, maybe they’ll gradually lose contact, or maybe they’ll keep texting each other forever. Regardless, they’ve got time to work it out. 

They’ve got time.

They were fighting. Arguing about something stupid. A science fiction movie that just hit theaters. Gen accused Sensei of being pedantic and Sensei responded that Gen just had poor taste. A variation on an argument they’d had dozens of times before. Gen just rolled his eyes, shoved his phone in his pocket, and charged onstage, ignoring the text notification that buzzed right as he started his act. Let Sensei talk to himself for a while.

He should have checked.

That’s all he can think as the world goes black and cold around him.

He should have checked his phone.


	2. Chapter 2

**Summary for the Chapter:**

> Everything is different now.

**Notes for the Chapter:**

> oh my goodness...this really got away from me. it careened wildly off the rails into completely unplanned territory, but I'm incredibly pleased with how it turned out and I hope you enjoy it too!!
> 
> several people expressed disappointment that the 2nd part wouldn't have text convos, but fear not! I loved writing them too much not to include some. the ones featured here aren't necessarily in chronological order and they don't always directly relate to the surrounding sections, but they do inform the narrative a bit more, plus they're just cute to read!! I think I ironed out all the formatting bugs, but if you see something weird, let me know!
> 
> (btw thank you Zenyr for pointing out those typos! you rock!) 
> 
> MAJOR SPOILERS FOR THE MANGA from here on out, guys. I'm serious, don't read if you don't want to be spoiled for the next season of the anime.
> 
> okay, that's enough from me. enjoy!

After the initial drama dies down and he’s already been conned into physical labor in the pursuit of electricity, he realizes that something about Senku seems very...familiar.

He doesn’t have much time to ponder the situation, especially when he’s too busy being murdered, but even then, lying on the floor of a hut and making absurd promises with a madman, Senku’s confidence strikes a chord somewhere inside him. He almost asks, as Senku helps him quietly slip his robe back on.

_Have we met before?_

But they’re short on time, and besides—Gen would definitely remember meeting someone as unique as Ishigami Senku.

He knows that Taiju and Yuzuriha are plants, of course; that much was obvious to him from the moment he first met them, soon after he was de-petrified, even before he knew anything about their supposedly dead friend. Nothing on them, though. They were doing an admirable job of playing the grieving-but-accepting converts to Tsukasa’s empire. Gen is simply uniquely suited to picking up on that sort of thing. As a result, he has to be careful how he interacts with them after he returns from the village. Spending too much time with them would tip his hand, but avoiding them would be equally suspicious.

Yuzuriha, at least, seems to understand what Gen’s presence means. Most of the empire knows he was sent to check on Senku’s status, and as one of the only other people who knows Senku is alive, Yuzuriha must realize that Gen’s report means he’s switched sides. Taiju seems oblivious to the whole thing, which is probably for the best.

When he’s not with Tsukasa, Gen often finds himself helping Yuzuriha with whatever she’s doing, usually sewing. After a childhood spent making his own costumes, Gen isn’t completely useless with a needle and thread, which is more than can be said about most of the people in Tsukasa’s empire.

It’s during one of these sessions that Yuzuriha asks: “Is there someone you’d like to find, Asagiri-san?”

It’s not exactly a taboo topic of conversation, even if everyone knows Tsukasa’s policy on depetrification, and people will sometimes speculate about the whereabouts of loved ones, or even appeal to Tsukasa if they think they know someone who would be a good fit for the Empire. Gen himself hasn’t given it too much thought. His family wasn’t exactly in the picture 3700 years ago. His manager can just wait as far as he’s concerned. And as for friends—

He really only had one.

“Not really,” he chirps in response, eyes on the felling stitch between his fingers. “I’ve always been fine on my own.”

“Oh, I see. That’s a good thing, I guess.” Yuzuriha’s tone dips and Gen looks up to find her smiling sadly, gaze distant. “I worry about my parents a lot. It can be distracting.”

It can’t be easy for her, Gen realizes. On top of everything that’s happening, she’s still grieving the loss of almost all the people she ever knew. Taiju was an orphan, and most of the people in the empire are fine with Tsukasa’s philosophy, so she doesn’t really have anyone to relate to. In an effort to encourage camaraderie with one of his few allies, Gen finds himself saying: “Well, there is one person.”

She perks up curiously. “Who?”

“A friend. Well, I suppose I would call him a friend.” Gen smiles wryly. “I never actually met him.”

“What do you mean?” she wonders, scooting forward slightly.

Gen feels himself flush inexplicably. He’s never actually discussed Sensei with anyone. How would he have even explained it? _One day, this guy texted me by mistake and I texted him back and we just never stopped?_ Talk about pathetic. Not to mention, it was kind of...private. Sensei was like this secret refuge from the rest of the world and Gen didn’t want to ruin that. Now, though, there was no reason to be precious about it.

“It’s kind of funny, actually,” he hums after a moment. “We only met because he texted the wrong number. Isn’t that strange?” he chuckles. “Anyone else would have just blocked the number and forgotten about it, but, well, things happened and—” he shrugs. “Truly, a friendship for the modern era. But I never even found out where he lived, so finding him would be...impossible.” Gen’s smile freezes on his face, the truth of that statement sinking in for the first time. Given the nature of their relationship and how the world has changed, the probability that he’ll ever talk to Sensei again is...incredibly low.

“Wait—” Yuzuriha is frowning. “He texted you by mistake? And then you kept texting? For how long?”

“Oh—uh—” Gen composes himself. “A little over a year, if I remember correctly.”

Her eyes widen.

“Isn’t that silly?” Gen continues, laughing intentionally. “Even thinking about that kind of thing seems so crazy now!”

“Asagiri-san,” she says seriously. “You’re...a performer, right?”

He blinks at the sudden shift in tone. “Among other things.” He returns her intense stare. “I thought you knew of me before the incident, Yuzuriha-chan.”

“I thought I did, too,” she mutters. “I think I still do.”

“What do you mean?”

“Asagiri-san,” she says slowly. “Do you think—”

“Gen-kun!” A familiar, sickly sweet voice cuts her off and they both jump, turning to see Hyouga striding toward them.

“Hyouga-chan!” Gen greets, passing his work to Yuzuriha wordlessly and rising, dusting himself off. Yuzuriha nods politely and returns to her sewing. “How can this humble metalist help you today?”

“Tsukasa-kun wants to speak with us.” Hyouga’s shrewd eyes rake him up and down and Gen represses a shudder of unease.

Tucking his hands into his sleeves, Gen smiles and pushes all thoughts of Sensei out of his head. “Lead the way, then.”

* * *

Sounds like a lot of hassle  
  
Yeah, troubleshooting has been a real bitch.  
  
Do you have people who can help you?  
  
A couple. They’re eager, but not really as technically-minded as I am.  
  
Wow, so polite from the guy who calls people idiots at the slightest infraction.  
  
One of them is definitely an idiot, but he’s useful in his own way.  
  
What about your father? Isn’t he a professor?  
  
Not really the hands-on type, and even his understanding of the theories I’m working with is shaky. Hence why he needs to STUDY  
  
Well, I’d be no help at all. Unless you like card tricks!  
  
Eh.  
  
That’s all I can offer, sensei   
  
I’m sure I’d figure out something for you to do. You don’t seem completely unintelligent.  
  
When it comes to that kind of thing, I’m totally hopeless.  
  
I can teach you.  
  
I’m not sure if that’s sweet or calculating.  
  
Science can always use extra hands. Sometimes literally.  
  
  
  
I’m amazed anyone hangs out with you.  
  
Childhood friends are obligated.  
  
How unexpectedly wholesome~!  
  
You better not be profiling me based on this information.  
  
Me~? I would never!!  
  
But I never read you as a total loner anyway, sensei. You’re far too well-adjusted.  
  
List the qualities that make you think I’m well-adjusted so I can eliminate them.  
  
I can’t give up all my secrets, sensei~!  
  


* * *

Things happen very quickly after the assault on Ishigami Village.

Gen’s ruse is up, which is fine by him, all things considered. Tsukasa’s empire was a stressful place to be, and he wasn’t much use as a spy with no way to pass information. He feels a flicker of concern for Taiju and Yuzuriha, but he trusts that Tsukasa won’t do anything to them. It isn’t his way.

Being with Senku is way more interesting, anyway. The kid’s intellect is dizzying. If Gen wasn’t already convinced of his lunacy by the carving he left outside of the Cave of Miracles, or his momentous victory in bringing electricity to the dark world, Senku’s cell phone declaration would have sealed it. As impossible as it sounds, however, Gen can’t help but believe it. If anyone can reinvent cell phones in the stone world, it’s Ishigami Senku.

Gen almost laughs wondering what Sensei would have to say about the whole situation. He’d probably agree with Senku: _if you just follow the steps, you’ll definitely get there_. He was always very utilitarian like that.

If there’s a drawback to joining the kingdom of science, it’s that it’s harder not to think about Sensei when he’s around Senku. On bad days, the way Senku talks, his intense and confident tone, echoes Sensei so much that it sits like a physical ache in Gen’s chest. On good days, the similarities are almost comforting, a touch of the familiar in a vast sea of the unknown. Dwelling on the matter is pointless, of course, but he can’t help it.

Senku’s excitement in the face of a challenge, his encyclopedic knowledge of science and natural processes, his eagerness to educate everyone around him, his smirking sarcasm— it’s all so _familiar_. Sometimes Gen can hardly stand it, but he can’t stay away.

What makes it even harder is that Senku seems just as interested in _him_. They’re all very busy, and Senku isn’t overt or anything, but Gen wasn’t a semi-famous psychic for nothing, and he can tell when Senku is intrigued by something.

For as much as Senku rolls his eyes at Gen’s abilities, he always seems to be around when Gen is doing tricks for the village kids (and Ginrou), watching with sharp eyes and a wry smile. He refuses when Gen offers to teach him some sleight-of-hand but pays close attention when Gen demonstrates anyway.

“There’s no shame in liking magic tricks, Senku-chan,” Gen says at one point, dropping the handful of nuts he just conjured into Senku’s palm. “They may even come in handy someday.”

“I’m not ashamed,” Senku replies, pulling a tool from his waist pouch and using it to crack the hard hull of one of the nuts. “And it’s not that I particularly like magic tricks or anything.” He offers the shelled nut to Gen. “Watching you just kind of reminds me of someone, that’s all.”

Ears perking up, Gen accepts the nut and rolls it between his fingers. “ _Someone_? I never expected the great chief of the kingdom of science to consort with _magicians_.”

“I consort with you, don’t I?”

“I’m a mentalist with magic powers, Senku-chan. There’s a difference.” Gen pops the nut in his mouth and smiles as he chews.

“Right, my mistake.” Senku busies his hands cracking the rest of the nuts.

Gen watches him carefully. “Did you know this person well?”

Senku shrugs. “Pretty well, I guess.”

“You guess?”

Senku glances up, a crooked smile making his eyes glitter. “Nosy.”

A shock zips up Gen’s spine. “Sorry,” he sings, betraying nothing. “You just make me _so_ curious, Senku-chan!”

“There’s nothing to be curious about.” Senku discards the empty shells and offers the rest of the nuts to Gen, who barely has time to hold his hands out to accept them.

“Trust me, if I could stop, I would,” Gen laughs, juggling his new handful of nuts.

Senku smiles and opens his mouth like he’s about to say something, but Chrome shouting from the lab distracts them both and the matter is dropped.

Christmas comes, bringing the first major test of the components for their cell phone, and as Gen blinks in awe at the illuminated tree, Senku steps up beside him.

“Why take the time?” Gen wonders.

He feels more than sees Senku shrug. “Nothing wrong with a little celebration. It pays to keep morale up.”

Gen smiles, watching Suika and the other kids run around excitedly, tugging the adults into their games, bathed in the light. “Of course, all in service to your vision.”

“We’re all stuck with each other, more or less,” Senku says. “Sort of like castaways surviving together. Or astronauts. And even astronauts celebrated holidays together.”

Gen blinks, a shiver of recognition flashing through him. He tucks his arms closer to his body, trying not to think of a time, thousands of years ago, that he made that exact point to someone in need of perspective.

“Cold?” Senku asks.

“Ah, a little,” Gen hitches his smile back up.

“No wonder. It’s snowing, after all.”

Gen casts a look at the little white specks drifting gently to the ground around them. “It actually feels like Christmas,” he chuckles.

Senku grins at him before Suika drags him away.

Senku’s birthday gift is no small feat, if Gen does say so himself. With both of the most scientific minds in the village away, it falls on him to do all the planning and technical work. He’s not a complete moron, but engineering isn’t exactly his wheelhouse. Regardless, with everyone’s help, they manage to get it done in time, and surprising Senku brings with it a rush so strong it makes Gen giddy enough to spill some of his true feelings.

He plays it off, thankfully, and Senku takes it in stride.

Once everyone else has retired, Gen hangs around, watching Senku fiddle with the telescope.

“How’d I do?” he asks, tucking his hands into his sleeves against the chill coming in through the open roof. “I didn’t get a lot of time to test it.”

Senku glances at him, smirking. “It’s pretty shoddy, but I’m actually impressed. It really magnifies. Where’d you learn telescope mechanics?”

“I wouldn’t call myself an expert or anything, but I did once suffer through a very long lecture on the fundamentals of telescopics. The mirrors and lenses and all that.” Gen smiles at the contraption, remembering how irritated Sensei used to get when he called it _the Hubble Kaleidoscope_ on purpose. “I just wrote down everything I remembered and Kaseki-chan did the heavy lifting.”

Senku hums, peering through the eyepiece. “Well, it works. Mostly.”

“High praise coming from you.” Gen steps up beside him, gazing up at the sky through the roof hatch. The stars are so much brighter now, in a world without artificial light, but he can still easily pick out Sirius, glowing the brightest of all of them. “Didn’t you say the positions of the stars have shifted?”

“Some of them. Some are too far for the Earth’s tilt to mean much, but the skies definitely look different now.”

“Well now, that’s a little melancholy, isn’t it? Kind of like the universe is saying things will never be the same again. ”

Senku straightens up, hands on his hips, and considers the sky alongside Gen. “Don’t get too depressed, mentalist. Everything changes all the time.”

“Yes, yes, I know,” Gen laughs quietly. “Sirius B comes along and messes everything up. Nothing is constant. You don’t need to comfort me, Senku-chan.”

Beside him, Senku goes very still. Gen slides him a sideways look and finds that his expression has gone rigid. Even in the cold glow of the stars, Gen can see how tight his jaw is.

After a beat, Senku seems to shake it off. “So you’re an astronomer too,” he says, not looking at Gen. “Pegged you as more the astrology type.”

“Whatever gave you that impression?” Gen giggles. “But you’re right. Everything I know about astronomy was forced on me by a friend of mine. The same one who lectured me about telescopes, actually. I wonder if I could still do horoscopes with the new stars.” He frowns thoughtfully at the ceiling of light above them.

“You could probably figure it out. Or make something up.”

“Want to give it a try, Senku-chan?”

“That kind of thing is a waste of time.”

“Ah, yes, of course, of course.” Gen lowers his head, smiling at the floor. Senku is just...so much like Sensei. His heart gives a pang of longing and suddenly he can’t be in Senku’s gravity well anymore. “Well, I’ll leave you to it. Happy birthday, Senku-chan.” He turns to leave.

“Gen—” Senku breaks off but Gen pauses his steps, looking up.

“Something wrong?”

“No, I just—” Senku scratches the back of his neck, brows furrowed and looking as uncertain as Gen has ever seen him. Backlit by the night sky, Senku’s eyes gleam like stars themselves. “I wanted to say thanks. I don’t think I said it before. So thanks.”

Gen tilts his head. “For what?”

“For—” Senku blinks, startled. He lowers his gaze, a small smile curling his lips. If Gen didn’t know any better, he’d say Senku looked sad. His lips move, like he’s mumbling to himself, but no sound escapes.

“Senku-chan?”

Senku glances up, expression back to his neutral smirk. “Don’t fish for compliments, mentalist. I’m not saying it again.”

“Right.” Gen chuckles. “Goodnight, then.”

Already turning away, Senku waves a dismissive hand. “‘Night.”

Gen casts him one last searching look before descending the ladder.

* * *

I’ve been sitting in this tech meeting for so long my legs have fallen asleep and I’m about to follow. PLEASE distract me.  
  
Did you know that the numbness of your limbs “falling asleep” isn’t due to lack of blood flow but actually pinched or compressed nerves?  
  
...no I didn’t know that. I always thought it was blood.  
  
If you lose circulation to a limb, it will start decomposing.  
  
Yikes!!! Just like that?  
  
The decomposition process starts as soon as the cells lose access to oxygen, which is delivered by the blood. So yeah, if you actually lost blood flow to your legs, they would rot off.  
  
Thanks, I’m awake now.  
  
Thankfully, that’s not what’s happening when a limb falls asleep.  
  
So what about tourniquets and stuff? First responders use those all the time.  
  
Tourniquets should only be used as a last resort. EMTs and doctors only use them if they’re willing to sacrifice the limb. Once circulation is gone, it’s incredibly difficult to reestablish it. Sometimes, that’s the only option, though.  
  
You’re seeeriously blowing my mind, sensei.  
  
Want to know the truth about vitamins?  
  
Truth? What truth?  
  
Sensei?  
  
Sensei, I take vitamins! Don’t do this to me!!!  
  


* * *

Working closely with Senku on their deception plan is an experience.

They spend several long hours alone together ironing out the details and even longer while Senku teaches Gen morse code. In the days leading up to Gen’s departure with the cell phone team, Senku drills him almost constantly, tapping messages onto his arm for him to decipher while they work.

Despite the distraction of having Senku constantly nearby and _touching him_ , Gen picks the language up quickly.

Thanks to Senku’s rotten luck, several things go terribly wrong during the whole operation, but Senku’s equally strong grasp on his own fate drags them back from the brink of disaster.

“I think you should let me do your horoscope after all,” Gen whines, slumping over the table after they finally hang up with Nikki. “I bet it’s like nothing I’ve ever seen.”

Senku smiles grimly. “Maybe someday. Where are Magma and Chrome?”

Gen buries his face in his hands. “We were cornered by Ukyo. I had to leave them to make it back in time. I don’t even know if they’re okay.” He bites his lip, still hiding his expression. He trusts that Ukyo won’t kill them, but if they get captured—

“Alright—” hands on his shoulders pull him upright and start guiding him toward the ladder. “Bed time.”

Startled, Gen drops his hands, unable to resist. “Ah—Senku-chan, it’s okay! We have to prepare, and I have to keep practicing for the next call—”

“How long have you been up?”

“How long have _you_ been up?” Gen counters, knowing full well that Senku has barely rested since they split ways.

“I haven’t been running through the woods for hours,” Senku shoots back. His grip is firm, his tone unyielding.

“Don’t deflect.”

“Suika!” Senku yells and the familiar melon rolls into view in the clearing below. “Make sure Gen goes to sleep.”

“Got it!” she chirps, already racing over to scramble up the ladder.

Gen shoots Senku a glare. “Sneaky.”

“What can I say?” Senku shrugs. “I learned from the best.”

Gen lets Suika herd him away, heart pounding.

The Kingdom of Science knows no rest, and, after Chrome is confirmed captured, they have to move quickly. Between shifting the entire village closer to Tsukasa’s stronghold and using the cell phone to trick members of the Kingdom of Might, Gen barely has time to think. Despite the seemingly insurmountable odds, however, Gen never feels the fear he expects. He’s scared, of course; he’s seen Tsukasa and Hyouga’s power up close, but Senku does everything with a certainty that overwrites even bad luck, and it’s hard to feel hopeless when you trust someone so much.

It’s trust that crams Gen into their paper tank alongside Senku, facing the full brunt of the Kingdom of Might head-on. It’s trust that drives him into the Cave of Miracles beside Senku when everything goes wrong. It’s trust that lets Senku take over the negotiations.

And it’s trust that keeps him from panicking when Senku and Tsukasa go into the river. Senku wouldn’t die from something like that.

He wouldn’t. Gen trusts that he wouldn’t.

It’s a little while before he actually sees Senku again. Tsukasa’s injury needs immediate attention and Senku isn’t exactly unscathed. Plus there are a million things to do in the aftermath of the battle, but Gen eventually makes it to the cave where Tsukasa is being treated.

Senku is fiddling with something when he gets there, Tsukasa sleeping more-or-less peacefully in front of him. He’s drooping wearily, but at the sight of Gen, he stands.

Gen doesn’t have the energy to fake snide disinterest as he meets Senku in the middle of the cave. “Are you alright?” he asks, gripping Senku by the shoulders and eyeing him over. He looks scuffed and battered, one hand wrapped in bloody bandages, but it seems as though Kohaku’s report was correct and Senku wasn’t seriously injured.

“I’m fine.” Senku grabs Gen’s wrists but doesn’t try to remove his hands. “Hyouga’s no big deal.”

“I’m supposed to be the liar, remember?”

Senku blows out a sound that’s almost like a laugh. “You saved my life, you know?”

That brings Gen up short. He meets Senku’s gaze with furrowed brows. “What do you mean?”

“Took a page out of your book.” Senku gestures to his abdomen. “I wrapped a sheet of batteries around my vitals. A spear-proof vest and stun gun all in one.”

Gen stares at him. “Well—” he collects himself. “Then all that awful work was worth it, I guess.”

“You guess?”

“Don’t go stealing any more of my tricks. I’ll lose my niche.”

“Don’t worry,” Senku chuckles roughly. “I’ll leave the near-death experiences to you from now on.”

“Don’t say that—” Gen grips Senku a little tighter, the corner of his mouth twitching up. “With your luck, I’ll be a ghost by noon.”

“As long as you hang around, that’s no problem. It’s not like you’re good for physical labor.”

“So cruel!” Gen releases one of Senku’s shoulders to pinch his cheek. “You’re definitely getting haunted for that.” Deja-vu prickles at the back of his mind but he ignores it. This is Senku in front of him right now.

“Don’t cry, mentalist,” Senku smirks.

Gen blinks, realizing his expression had indeed crumbled and his eyes are wet. “Please, who would cry over you!” But his smile is wobbly. The hand on Senku’s face softens until it’s cupping his cheek.

Senku’s sharp smile hardens into an intent line, his eyes blazing.

“Forget about this—” Gen mutters before wrapping his arms around Senku’s neck and pulling him in. It’s not how Senku does things, he knows. This kind of overt display isn’t familiar for either of them, but after everything, Gen just needs something _solid_ , just for a minute.

After a suspended second of rigid stillness, Senku seems to relax, just a bit, and Gen feels Senku’s hands settle firmly on his back. Senku exhales, the air brushing Gen’s ear. “Don’t cry,” he mutters.

Gen tightens his grip, ducking to press his face into Senku’s collar. “Not crying,” he insists, voice muffled.

Hugging Senku is strange. It’s obvious that neither of them are really used to it, but when Senku presses his cheek against the side of Gen’s head and curls his fingers into the back of Gen’s robe, Gen thinks he wouldn’t mind staying in this weird, awkward circle of warmth forever.

Of course, they can’t. Behind Senku, Tsukasa stirs, and the sound startles them away from each other. Shaking off the lingering emotional haze of the moment, Gen hurries past Senku, deeper into the cave.

“Tsukasa-chan! I was so worried!”

“Gen—” Tsukasa croaks. “I am glad to see you again, despite the circumstances.”

“Oh, you always know just what to say.”

And his little breakdown is forgotten in the face of everything they have to do.

* * *

How do you make two people realize their feelings for each other?  
  
owo what’s this? Is Sensei experiencing the adolescent flutterings of ~love~?  
  
Gross. Not me. Just two people I know.  
  
Do you know them well?  
  
You could say that.  
  
And you know they like each other?  
  
It’s painfully obvious.  
  
To everyone but them, apparently  
  
And they’re your age, correct?  
  
Yes.  
  
Hmmmmm  
  
Well, I’m afraid there’s nothing to be done, sensei!  
  
I thought you’d have some sort of psychological trick I can use to make them get it over with.  
  
Sorry, sensei, but this kind of thing can’t be rushed.  
  
I could coach you on ways to manipulate them, but you like both of these people, right?  
  
Unfortunately.  
  
So any trickery could backfire on your relationship with them. People like that have to work these things out for themselves. If it’s really affecting their lives, however, you should try to speak honestly about it with them.  
  
I’m not sure what to say. That’s shockingly reasonable coming from you.  
  
Hey, I know real psychology and neuroscience! It’s not all cunning and manipulation all the time!!  
  
I can see that now.  
  
Sensei is so mean!!!  
  
I guess I just think they’d be happier if they got on with it.  
  
They probably would be, but they wouldn’t appreciate you meddling. Unless one of them comes to you for help, or you’re worried about them, you should stay out of it.  
  
You seem like the type who needs to be in control, so that will probably be hard for you, but give it a try.  
  
Alright, enough profiling me. I didn’t come here for that.  
  
Am I wrong~?  
  
This whole ordeal is more trouble than it’s worth.  
  
What, love?  
  
Love, relationships, feelings in general.  
  
I’m not surprised that someone as driven as you would think that way.  
  
I don’t have the patience for distractions like that.  
  
That’s fine, sensei! Nobody is going to make you fall in love.  
  
From what I can tell, if it happens, it certainly won’t be up to me.  
  
Ah, yes, and you’d hate that.  
  
Since you need to be in control.  
  
I’m warning you.  
  
  
  
And I’m warning that little gray box.  
  
You’re young, sensei. There’s no need to rush on this stuff. If you don’t wanna bother with it now, you don’t have to. No one’s pressuring you, are they?  
  
As if I’d put up with something like that.  
  
High school is dangerous! You can never be too careful.  
  
Yeah, you seem like the type that was bullied in high school.  
  
You come to me for advice and this is how you treat me?? So cruel!!!  
  
And I’ll have you know I was NOT bullied in high school.  
  
Right.  
  
Which of us is supposed to be the psychology expert?  
  
I’m really not sure anymore  
  


* * *

Merging with the Kingdom of Might goes smoother than anyone expected, probably due to Tsukasa and Senku’s obvious regard for each other. If Tsukasa trusts him, the rest of the empire is inclined to as well, even after Tsukasa is frozen, but Gen keeps an ear out for potential conflict.

Fortunately, nothing arises that a little smooth-talking can’t fix, and keeping Yo and Magma pitted against each other effectively distracts them from potentially sowing discord among the others.

Once plans for the Perseus are underway, Gen doesn’t see Senku as much. It’s to be expected, he figures. Senku is the brains behind the huge operation, after all, plus he’s reconnected with his old friends and doesn’t need to lean on Gen as a fellow modern man as much. Perfectly understandable. Gen tries not to think too hard about it.

After a grueling day of digging the shipyard, Gen deposits Suika back at her hut and heads for the cave Senku has taken over for his drafting, a new stack of paper piled in his arms. As he approaches, the familiar sound of Taiju’s excited voice greets him and he pauses just outside the entrance, unable to resist the temptation to eavesdrop.

“—know we’re busy, but things are way calmer now, so I think—”

“Since when do you _think_?” Senku cuts in, and Gen’s ears perk up at his uncharacteristic harshness. Senku is biting and sarcastic, but Gen rarely sees him actually lose his temper. Now, though, he sounds truly irritated.

“—we should try to find them,” Taiju continues, unperturbed. “I mean, it couldn’t hurt.”

Gen hears the sharp scratching of pencil on paper but no response.

“Dude,” Taiju tries after a second. “Come on. I _know_ you miss them.”

“So what? Everyone here is missing someone. What makes me so special?”

“Senku—”

“And where would I even start?” Senku barrels forward. “They could be anywhere in Japan. Or—there are Japanese speakers all over the world, they could be _anywhere_ —you think I should waste time on a wild goose chase?” He huffs. “And that’s ignoring the fact that I have no idea what they look like.”

“Aren’t you worried about them?”

“Taiju, stop—”

“I’m not a mind-reader like Gen, but I know you miss them. You have to! You were so close—”

“That doesn’t change anything.” Senku sounds like he’s speaking through his teeth.

“Surely, you’ve got some way to find them. Some detail or _something_ —”

“No.”

“Everyone else is looking for statues they know, so why—”

“Taiju, there’s nothing!” Gen jumps at the sudden vehemence in Senku’s voice. “Don’t you think I’ve tried to figure it out? Don’t you think if there was some chance of finding them, I’d have done it already? I’ve been over and over it and there’s nothing.”

“So you’re just giving up?” As always, Taiju matches Senku beat-for-beat. “You’re probably the only person in the world who _could_ find them with nothing and you’re not even going to try?”

“I don’t want to talk about this anymore.”

“You’re just cool with never seeing them again?”

“I’ve never seen them at all!”

“Senku, you always said you—”

“Stop!”

“Did you just turn those feelings off?”

“Do I have any other options? Even after we re-establish society, the odds of us finding each other are virtually nothing! I can’t afford to sit around and—and _pine_ like an idiot when there’s nothing to be done!”

Gen stares at the ground, eyes wide. He’s never heard Senku this worked up, a painful mixture of anger and despondency that almost hurts to listen to. And the revelation that Senku had someone so important in his life that he now has no chance of seeing again—

It strikes a familiar chord of sorrow that Gen thought he had buried completely.

“Drop it,” Senku is saying, accompanied by the rustling of paper. “I don’t want to hear about this again.”

Taiju growls and heavy steps sound on the stone. Gen has a brief second to arrange himself before Taiju is striding out of the cave, nearly bumping into him.

“Oh, Taiju-chan!” Gen says, acting like he just walked up. “Sorry, I didn’t see you there.”

Taiju just nods and maneuvers around him, stomping off down the path. Gen watches him go before ducking into the cave. “What put a bee in his bonnet?” he asks.

Senku is hunched over his makeshift drafting table, body language closed, eyes down. “No idea,” he says mildly.

Gen hums. “I brought more paper.”

“Thanks. Just put it anywhere.”

Settling the stack on a shelf, Gen glances over his shoulder at Senku’s tense figure. “Trouble in paradise?”

Senku doesn’t react, reaching for a tool that looks like a handmade compass. “Don’t know what you’re talking about.”

“Oh, you know—” Gen wanders closer, folding his hands together, “—I would just hate to see the stone world’s cutest couple break up over something silly. If you and Taiju-chan are having problems, I’m always willing to lend an ear.”

“What makes you think we’re having problems?” Senku asks, not looking up.

“Taiju-chan seemed _so_ upset a minute ago, and you’re the only one in here. I don’t need to be a scientific genius to put two and two together.”

“Your math needs work.”

“The Kingdom of Science will surely crumble if two of our pillars are at odds! I’m only trying to—”

“Gen—” Senku finally looks up, fixing Gen with a hard stare. “Let it go.”

Gen regards him. Senku’s expression is firm. “Alright,” he relents. “It’s your business.”

After a beat of intense eye-contact, Senku returns to his sketching, and the rough scratching of the pencil fills the silence between them. For a brief, insane second, Gen considers blurting out the truth, that he cares about someone he has no chance of meeting again, but that would just tell Senku that he was eavesdropping, and, besides, what would be the point? Commiseration? As if Senku has ever been interested in that. The last thing Gen wants is for Senku to think he pities him.

So Gen shoves the urge aside and sweeps out of the cave.

* * *

That’s it! I’m quitting show business!!  
  
Good for you. It’s about time.  
  
Sensei, do you know how to kill someone and make it look like an accident?  
  
Are you seriously asking?  
  
Yes.  
  
Oh boy. Strap in.  
  
Injecting air directly into the blood will cause an embolism and is virtually undetectable in an autopsy. Staging a carbon monoxide leak is easy and looks like an accident. Potassium chloride is deadly and mimics a heart attack. Gradual lead poisoning is risky if you get caught part-way through, but it’s worked before. Aconite is only detectable through extremely in-depth analysis and you only have to use a little for it to be fatal.  
  
Of course, people fall and die all the time, so if you see a chance, take it.  
  
Thanks, sensei. I’ll have to block you and delete this chat now.  
  
Finally, I’ll be free.  
  
What made you decide to quit show business/commit murder?  
  
A man three times my age called me “sweetheart” and tried to touch my hair today   
  
Oh. Ew.  
  
He’s lucky I’m so nice!! I almost cursed him on the spot, but then everyone would know it was me.  
  
Right.  
  
If you know his email, I could send him a virus or something.  
  
Aw, that’s so sweet, sensei~  
  
But he’s a bit of a big name in the industry. You could trace him back to me. And that would ruin this fun mystery we’ve got between us.  
  
Plus this kind of thing happens all the time, unfortunately.  
  
Let me know if you change your mind.  
  
You’ll always be the first person I turn to if I need to break the law.  
  
Nothing illegal about sending an email.  
  
  
  


* * *

Senku seems to feel contrite about his argument with Taiju, and, a few days later, Gen catches him allowing Taiju to subject him to a massive hug, complete with manly sobbing and tearful gibberish, as always. It’s a heartwarming sight that Gen makes sure to mock Senku for mercilessly at the first available opportunity. Senku just smiles and snipes back and Gen is relieved that things seem back to normal.

His relief turns to confusion when Senku tosses him what appears to be a thick paper envelope.

“What’s this?”

“Just open it.”

Suspicious, Gen peels open the sachet and peers inside.

“It’s not poison, mentalist,” Senku groans. “Just get on with it.”

“When it comes to you, one can never be too careful, Senku-chan.” But Gen complies and tips the envelope over his hand. A thick stack of small papers lands in his palm, bound with twine, and Gen’s eyes widen. “A deck of cards?” he asks in disbelief.

Senku shrugs. “Figured a lying gambler like you would need some at some point.”

Nearly vibrating with excitement, Gen unties the cards and spreads them out, taking a quick mental count. It’s a full deck of 52 cards, plus 2 Jokers, made of some sort of stiffened paper, and complete with scientific terminology and little drawings on the face cards. He laughs when he notices the Jokers both sporting his petrification scars. “Did you draw these?”

“Maybe.” Senku crosses his arms. “Is there something wrong with that?”

“Of course not!” Gen sings. “I always forget how _very_ talented you are, Senku-chan. A true renaissance man!”

“Yeah, yeah.” Senku rolls his eyes.

“Thank you,” Gen says earnestly. “They’re perfect.”

Senku turns away, back toward whatever project he’s working on, and if Gen didn’t know better, he’d say the tips of Senku’s ears look red.

Ryusui is a surprise. Ryusui reintroducing capitalism is less of a surprise, honestly, given what Gen surmised about the man upon first meeting him, but it’s no problem for Gen. After a few initial hurdles, he figures out how to make Ryusui dance to the preferred beat and all is well.

He’s a little less adept at managing how affectionate Ryusui is compared to everyone else. It’s obvious that Ryusui is a lover of many things, an aspect that makes him easy to control, and that affection quickly spreads to his new comrades. Even Senku isn’t immune, unable to dodge all of Ryusui’s manly back slaps and excited hugs.

Gen is no exception, though he’s better at staying an arm’s length away, trained from years around grabby entertainers and show business personalities. He can’t always escape, though, and he frequently finds himself with a muscular arm around his shoulders or unceremoniously hoisted off his feet if Ryusui deems it more efficient for whatever they’re doing.

He endures it gamely, unable to deny that Ryusui has a magnetism that rivals even Senku’s in its ability to make people like him. Unfortunately, he has to draw a line when Ryusui absently reaches over to ruffle his hair while they’re all sorting a huge stack of newly made bolts, weeding out ones with too many imperfections.

“Ah—” Gen ducks quickly away, still smiling. “Sorry, Ryusui-chan, but if you touch my hair, I _will_ have to curse you.”

“I see,” Ryusui says astutely. “I’ll keep that in mind.”

A metallic clatter draws Gen’s attention to Senku, who has apparently tipped his basket of rejects over onto the table. “Everything alright, Senku-chan?”

“Yeah,” Senku says shortly, righting his basket and scooping the little metal pieces back into it.

“Don’t be scared, Senku,” Suika pipes up. “Gen can’t _really_ curse people!” She aims her helmet at Gen, who can picture the wide, glistening eyes behind her thick lenses. “Right?”

He smiles disarmingly at her. “Don’t worry, Suika-chan. I’d never put a curse on _you_.”

“I’m not scared,” Senku insists, as though the very idea is preposterous. He glances at Gen, and Gen recognizes the calculating glint in his eyes. “Gen, did you go to college?”

Gen blinks. Senku rarely requests personal information, and he never makes smalltalk. “Oh? Trying to dig up dirt on your favorite mentalist? I’m not sure if I should be flattered or frightened.”

“Don’t be anything,” Senku scowls. “I didn’t mean anything by it.” And he returns to his sorting, brows pinched.

Gen eyes him curiously. It’s not like Senku to get down. He regards that kind of wallowing as unproductive and refuses to engage in it, no matter how tired or disheartened he may be.

But then Ryusui is grandstanding about something loudly right next to him and the moment is over.

Gen trusts Senku’s abilities absolutely, but the prospect of sending him, Chrome, and Ryusui up in a handmade hot air balloon admittedly makes him a little nervous. He mentally recites Senku’s simplistic explanation of how the contraption works, along with what he remembers from Sensei’s little lectures on aviation and safe cruising altitudes but he just can’t talk himself out of his nerves.

He’s standing to the side as they prepare for take-off, arms tucked close, watching, when his ruminations are interrupted by a now-familiar arm around his shoulders.

“Don’t look like that, Gen,” Ryusui says jovially, as though he didn’t just nearly send Gen off his feet with his enthusiasm.

“Look like what, Ryusui-chan?” Gen asks, smiling up at him.

Ryusui gestures vaguely to his own face. “Like that.”

“You must be seeing things. Perhaps you should stay down here after all—”

“He’s looking, you know,” Ryusui interrupts, pointing surreptitiously at Senku, who seems absorbed in some complicated ropework on the basket.

“What?”

“If you’re nervous, he’ll be nervous.”

Gen nearly scoffs at that. “That’s preposterous, Ryusui-chan. You clearly don’t know Senku-chan very well.”

Ryusui shrugs, the motion jarring with one of his arms still wrapped around Gen. “Smile anyway. Who doesn’t want to be sent off with a smile?”

“I’m always smiling, Ryusui-chan.”

“Then fake it a little better.” And with a pat, Ryusui releases him, charging toward the hot air balloon.

Gen watches him go with narrowed eyes.

He doesn’t tell Senku to be careful, or wish him luck, because he would just say something pithy in response, but when Senku approaches him inexplicably right before lift-off, he heeds Ryusui’s words and pastes on a wide smile.

“Aviation is a ladder, right?” Gen says, echoing something Sensei once told him. “I know it’s still far off, but this is a step toward space.”

Senku blinks dumbly at him for a second before his face cracks with a crooked grin and he shakes his head. “No need for inspirational speeches, mentalist.”

“Aw, isn’t that why you keep me around?”

“Yeah, that’s the only reason.” He scratches the back of his head and gestures at the balloon slowly inflating behind him. “You’ll be next.”

“Next?” Gen frowns.

“I’ll get you up there with me sooner or later.”

Gen gapes at him. “Th—that is a threat! I’m perfectly comfortable here on the _ground_ where I’m not in danger of plummeting to my death at any moment, thank you very much!”

Senku chuckles. “We’ll see.”

“We won’t!”

“Senku!” Chrome calls, waving wildly from the basket, Rysusui lounging artfully beside him. “Come on!”

Before he realizes he’s doing it, Gen’s hand shoots out and wraps around Senku’s wrist. They both look down at it.

“Uh—” face warming, Gen tries to pull away, but Senku catches him, clasping their hands together. He looks just as surprised as Gen when Gen meets his eyes.

“This—” Senku starts, stops, swallows, tries again. “I’ll see you soon.”

Gen’s grip tightens compulsively. “Yes. See you soon.” He hitches his smile back up. “One small step for man, and all that.”

“Right.” Senku smiles and starts to step away.

For a single, burning second, with now-ancient news stories of ballooning accidents and the long tragic history of the whole exploit running through his mind, Gen is consumed by the almost irrepressible urge to yank Senku back, grab him by that ridiculous hair and lean forward—

Then Senku slides his hand out of Gen’s and Gen watches him walk toward the basket, breathless from the full-body insanity he just fought off.

He’s still staring long after the balloon has risen into the sunrise.

* * *

HI!!!! THIS IS TAHDOAIDFJ;LS  
  
Sensei? Are you alright?  
  
NSJYS;SAL;Akskdhlssu  
  
???  
  
Sorry about that. One of my friends took my phone.  
  
Oh?? Put them on! I’d love to talk to someone who can manage being friends with you.  
  
Absolutely not. He’s an idiot and he’ll say unnecessary things.  
  
Well now I’m curious. What unnecessary things?  
  
Sensei?  
  
Aw, did you slip up~?  
  
No, it’s nothing like that.  
  
Stop making that face.  
  
What face? You don’t even know what I look like!  
  
I can tell you’re smiling like an idiot.  
  
No you can’t.  
  
I can.  
  
Okay, you’re right.  
  
I’m smiling like this (¬‿¬)  
  
Yeah, I knew it. And I only meant he would say random bullshit.  
  
Suuuuure, sensei. Whatever you say!!  
  
Why did he take your phone anyway? Just to text me?  
  
Yes. He and one of my other friends found out that I’m texting you and they’re inordinately curious.  
  
I’m so flattered~!  
  
I’d love to talk to your friends, sensei. Shame on you for keeping us apart!!   
  
I don’t want you guys anywhere near each other.  
  
Well, we won’t be NEAR each other.  
  
No.  
  
Don’t be so stingy! Worried I’ll steal them with my irresistible charm~?  
  
Okay, that made me laugh. Tell me another.  
  
So cruel!!  
  
You know they’re just interested in your life, right sensei?  
  
TOO interested.  
  
They seem like good friends and they just want to be included. You text me often enough that they’ve noticed, so naturally they’re curious about this mystery person you’re talking to. You have to admit, our acquaintance is a little...unusual. If it was MY friend, I’d want to make sure everything was above board too.  
  
I don’t need to be monitored. They’re just being nosy.  
  
Aw, you don’t really think that. You’re lucky to have such caring friends.  
  
Jealous?  
  
Sooooo jealous!!  
  
Yeah. You should be.  
  
Tell your thieving friend I said hi!!!  
  
He says hi back.  
  
  
  


* * *

The night after the balloon takes off, a few minutes after Senku’s check-in call from Ishigami Village (complete with an excited recount of their dangerous mid-air mishap), Yuzuriha sidles up to him, looking more nervous than usual.

“Gen-san, can I talk to you?” she asks.

He scans her covertly as he smiles. “Of course, Yuzuriha-chan. Whatever can I help you with?”

“It’s not really—I don’t need—can you follow me?” she gets through the question haltingly, but she gets through it, and Gen surmises that her anxiety is secondary to her determination to have whatever conversation she’s trying to get out of him.

He gestures with one of his sleeves. “Lead the way.”

She takes him to the hut where her massive loom sits, currently still and silent, and flicks a few lights on, indicating for him to take a seat on a pile of furs in one corner. He does and watches curiously as she settles herself beside him, fidgeting.

“Is everything okay?” he opens with.

“Yes, everything’s fine!” she says quickly.

“You seem very tense, Yuzuriha-chan.”

“I am—I am, but—” she takes a deep breath. “I should have talked to you sooner, but—” she twists her fingers in her lap. “We’ve been so busy, and, to be honest, I—I was worried.”

Gen cocks his head. “This sounds very serious.”

“It kind of is. It really, kind of is, but I thought I was just imagining things and I had mostly decided to just leave it alone, but then Taiju told me about his fight with Senku and I—I—” she presses her hands flat against her thighs and levels Gen with an intense look. “Gen-san, a long time ago, you told me about someone you knew, before the event, that you only talked to through text, right?”

Gen stares at her, his stomach curling unpleasantly. “Yes, I do remember mentioning that.”

“Can you tell me more?”

“More?”

She nods. “As much as you can.”

Gen shifts his weight. “Why do you want to know, Yuzuriha-chan? It’s really not a very interesting story.”

“Gen-san—” her eyes are shining in the lamplight. “Please.”

It’s an absurd request. Why would Yuzuriha care? Curiosity? Collecting blackmail material? As soon as the thought crosses his mind, Gen dismisses it. Whatever agenda Yuzuriha is working from, her intentions are pure. Anyone can see that. It’s in the earnest rigidness of her spine, the way she’s leaning forward slightly, the trembling of her lips.

Gen sighs. “Very well. How could I refuse the request of such a cute girl?”

And he tells her everything. The very first mistaken text, the strange non-relationship they developed, the gradual graduation to actual friends, the reluctant admissions of care, that last stupid, _stupid_ argument—everything.

It’s almost cathartic, in a way. Gen knows all about the mental benefits of therapy and counseling, the need humans have to _talk_ about things, but he’s never been in a position to test any of that for himself. Now, spilling all of his memories of Sensei to Yuzuriha, he feels a little pressure leave his shoulders with every word. He’s tried so hard not to think about Sensei at all since the world ended, but now it all comes flooding back.

Yuzuriha listens in rapt silence, each story pulling her body language taughter like a bowstring just waiting to loose a single, devastating arrow.

When he catches himself choking up with frustration while recounting their last exchange, Gen clears his throat, folding his hands in his lap. “Well, that’s the long and short of it,” he finishes, smiling blithely at his captivated audience. “Nothing too crazy, I’m afraid.”

Yuzuriha looks as though a sharp tap would shatter her all over the floor. “This—this Sensei person—you cared about him?” she asks tremulously.

Gen taps his chin. “Yes, I suppose. As much as you can care for someone in that situation, anyway. Why are you so interested in this, Yuzuriha-chan?”

“Gen-san, please be honest with me—” she leans forward so intently that Gen nearly startles backward. “Do you miss him?”

“What—what is the point—”

“ _Please_.”

Gen’s heart stutters in his chest. “Yes,” he confesses, holding her searing gaze. “He was my closest friend. I miss him all the time.” This time, the smile that curls his lips is thin and wry. “Pathetic, right?”

She shakes her head, clasping her hands in front of her. “No, it’s not! It’s not! It’s wonderful!”

“Wonderful?” Gen repeats. “I’m afraid I don’t see how—”

“Gen-san!” She’s positively beaming now. “I know who Sensei is!”

Gen blinks. “I’m...sorry? How is that possible?” But he can’t help the little bubble of hope that swells inside him.

Yuzuriha laughs delightedly. “I could hardly believe it myself! The probability—it’s fate! It must be fate!” She bounces back on her heels. “Oh, he’s going to be so _happy_ —”

“Yuzuriha-chan, please, put me out of my misery,” Gen pleads, watching her with mounting trepidation. “Who is it? Do you know where he is? Can we find him?”

She shakes her head, grinning. “We don’t need to find him! Gen-san—Sensei is Senku!”

Gen’s breath freezes in his lungs. “What?” he rasps.

She’s still jittering with glee. “This is so exciting! It’s kind of weird—you always seemed a little familiar to me, but I thought it was because I saw you on TV, and when you told me about your friend, I always wondered—but I thought that was too much of a coincidence! But still!” She beams at him. “Here you are! It’s—it’s nice to finally meet you!”

Gen wants to protest, to explain that it’s simply not _possible_ for Senku to be Sensei, but the words won’t come out. Because the puzzle pieces are assembling in an irrevocable cascade, one into another into another—Sensei’s father studying to go into space, Sensei’s two childhood friends with feelings for each other, Sensei’s obsessive pursuit of knowledge, Senku’s cryptic argument with Taiju—until Gen is faced with the whole picture.

It’s unbelievable. But it’s undeniable. Sensei is Senku.

Yuzuriha is still babbling excitedly but Gen can only stare at her, brain whirring as it tries to process this new reality.

“What—” he starts after a second, and she breaks off instantly, leaning forward. “What do I do now?” he asks quietly.

She tilts her head. “What do you mean?” Her eyebrows pinch together. “Are you okay? You look a little lost.”

Gen laughs humorlessly. “I...I am lost. What am I supposed to do? What does this mean?”

“Gen-san—”

“I can still barely believe it—that kind of coincidence—is it even possible?”

“It’s a miracle,” she insists.

Gen squeezes his eyes shut for a second, and when he opens them again, he’s smiling. “Sorry, Yuzuriha-chan. I forgot myself for a minute there. I’m just so shocked!”

She frowns. “Gen-san—”

“Thank you for telling me! What a crazy story, right?”

“Gen-san, are you okay?”

“Of course, Yuzuriha-chan!” Gen rises smoothly. “Anyway, we’ve had a long day. You should get some sleep. I’ll leave you alone—”

She scrambles up beside him, catching his sleeve. “Gen-san—” her eyes are wide and glistening. “Are—are you going to tell him?”

“If it comes up, I might mention—”

“He really cared about you,” she interrupts, curling her fingers tighter into his sleeve. “ _So_ much. He talked about you all the time. And he misses you, I _know_ he does. He’d be out there looking for you if, well, if it was possible—and even then, I know he wants to find you.”

Gen keeps his gaze fixed carefully over her shoulder. “He wants to find his silly wrong number friend.”

“That’s _you_!”

“I don’t think it is anymore.”

Her face crumples. “Gen-san—”

“I need to think about this, Yuzuriha-chan,” Gen says honestly. “Thank you for telling me. I have been worried about what became of Sensei, and I’m relieved to know he’s okay. But I…I need to think.”

After a tense second, Yuzuriha nods and releases him, clasping her hands against her chest. “I’ve wanted to be friends with you for so long, Gen-san,” she whispers. “Since before I even met you in Tsukasa’s camp. I’ll keep quiet to Senku if you want me to. And if you ever want to talk—” she offers him a watery smile. “I’m here.”

“Thank you,” Gen forces out. Then he all but flees from the hut, his heart in his throat.

* * *

Can you cook?  
  
ExCUSE me?  
  
The audacity. The gall.  
  
Can I cook??? Who do you think I am??  
  
I have literally no idea who you are.  
  
That’s no excuse!  
  
You haven’t answered my question.  
  
Because it’s preposterous! Of COURSE I can cook. I’ve been living by myself for years.  
  
Honestly sensei.  
  
This is a lot of indignation for seemingly no reason  
  
You’re not lying, are you?  
  
Sensei, I would NEVER lie to you.  
  
Right.  
  
Name a time I lied to you.  
  
I wasn’t disagreeing with you!  
  
Because it’s never happened!  
  
So what kind of things do you cook?  
  
Why are you being so nosy all of a sudden?  
  
Why are you avoiding the question?  
  
The nerve!! I’ve never been so insulted!!  
  
Yeah, this is about how I expected this conversation to go.  
  
WHY are you asking?  
  
My friends said I should ask you more questions about yourself.  
  
So you open with cooking? Are you interviewing a housekeeper?  
  
Wait, are you curious about me, sensei?  
  
Did you miss the part where I said my friends put me up to this?  
  
Just admit you’re interested in me!  
  
Unlike you, I don’t lie.  
  
But you’re fine with UNFOUNDED ACCUSATIONS, I see.  
  
Okay, fine.  
  
The truth is I can only do the basics. Enough to survive on, but I’m not a gourmet or anything.  
  
I’m really good at a few western dishes I learned in America though!  
  
Now was that so hard?  
  
What about you? Can you cook?  
  
Cooking is just science. I can do anything with a recipe.  
  
But what about ~experimentation~?  
  
I’m not allowed to do cooking experiments anymore.  
  
Let me guess~you exploded your kitchen and your dad banned you.  
  
Sensei?  
  
That’s it, isn’t it?  
  
Personal sharing time is over.  
  
Awwww   
  
  


* * *

There’s plenty to do. With Senku, Chrome, and Ryusui away, a lot of leadership duties fall to him, so it’s not like Gen has time to dwell, especially once the farming effort starts in earnest.

And yet, dwell he does.

Yuzuriha, true to her word, keeps the whole thing to herself but can’t seem to resist shooting him baleful glances at least a few times a day. Gen just smiles and acts natural, but in private, he _dwells_.

He can’t pin down how he feels about the whole thing, cycling through stages of frustration, anger, confusion, and mortification. Now that he’s on the other side of it, he realizes he _should_ have known. All the signs were there, and hadn’t he felt instinctively that Senku was familiar to him? If only he’d trusted his gut and actually paid attention, he wouldn’t be boiling with humiliation and inexplicable dread.

And Senku! Does he know? His argument with Taiju suggests he didn’t at first, but what about now? That probing question a few weeks ago—did he figure it out then? Gen knows he’s parroted things Sensei told him—would Senku remember well enough to pick up on that? Would he even care? Yuzuriha and Taiju both seem to think Senku misses his texting buddy, but does he? _Really?_ What if he knows and he just doesn’t care? Maybe their quote-unquote relationship pre-petrification was only important to Gen—but no, that’s just destructive thinking. Senku had to like him at least a little, right? He wouldn’t have kept texting him otherwise. So Senku, straightforward, no-nonsense Senku, probably doesn’t know, but does that mean Gen should tell him? What would be the point? But Senku did seem worried when Gen overheard him in the cave—

Questions and memories and justifications run around and around, arguing with each other and spinning Gen’s brain in circles as he lays awake at night, staring at the ceiling. But there’s no conclusion, no aha moment. All of Gen’s mentalist powers combined can’t conjure anything more substantial than a string of vehement curse words that plays like a record every time he thinks about the whole thing.

And before he can get any further than that, Ryusui needs them to find his mysterious butler, who then takes off into the wilderness, basically forcing Gen to follow them all the way back to Ishigami Village because what else is he going to do? Let this strange tiny person wander the forest alone minutes after awakening from complete petrification? Gen might not want to see Senku right now but he’s not that cruel. (Plus he really can’t take Yuzuriha’s well-meaning smiles anymore.)

“Been a while,” are Senku’s first words when Gen limps up to the group surrounding the makeshift oven while Francois, seemingly unperturbed by the long walk, inspects their sorry attempt at bread.

Gen flashes him an exhausted smile. “We talked on the phone the day before yesterday.”

Senku crosses his arms. “That’s not the same.”

He’s right; now that Gen is back in Senku’s atmosphere, after the longest time they’ve spent apart in over a year, he feels like a moon settling back into orbit. He’d been so preoccupied with his own thoughts he failed to realize how much he missed the pressure of Senku’s gravity constantly at his side. A warmth where he didn’t even know he was cold. There’s really nothing like it.

So Gen straightens up and grins. “I hope you didn’t have too much fun without me, Senku-chan.”

“Oh, yeah, map-making, _so_ fun.” Senku grins back and then they’re just standing there, grinning at each other like idiots.

Until Gen clears his throat. “Anyway. Bread?”

“Right. Bread.”

Francois quickly proves to be the best possible addition to the kingdom. They’re competent, efficient, intelligent, and nice to Suika, so Gen takes to them quickly as well. The only downside is that Francois is way too perceptive and the third time they purposely leave a room so that Senku and Gen can be alone, Gen realizes he might have a problem.

“Am I really that obvious, Francois-chan?” he asks, reaching for another handful of dried berries.

Francois doesn’t even look up from the dough they’re kneading. “If you’re worried that the others have picked up on your feelings for Ishigami Senku, do not fear. I am merely attuned to slight shifts in behavior. It is my duty as a butler to read my master’s every whim, sometimes before even he is aware of it.”

“Ah, I see.” Gen presses the berries into his own dough mechanically.

“This concerns you?”

“Well, it’s not really something I like to think about. Knowing that someone else knows—” he smiles blankly. “I’m not thrilled about that.”

“Rest assured, I am the only one who has picked up on it.”

“That’s somewhat of a relief, but, really, Francois-chan, you don’t have to play matchmaker.”

“My apologies for any confusion, Asagiri-san—” Francois settles their dough in a perfect little mound and looks up, fixing Gen with a steady gaze. “My matchmaking hasn’t been in response to _your_ feelings. I have been acting on Ishigami Senku’s desires.”

Gen’s hands reflexively dig into the dough. “I’m sorry?”

“Throughout my interactions with him, I have surmised that Ishigami Senku wishes to spend more time alone with you, thus I have endeavored to fulfill that desire whenever it is within my power to do so. Initially, I concluded that you share this wish as well. If I am mistaken, of course I will defer to you.”

Gen stares at the dough squishing out between his fingers. “Excuse me?”

“Again, my apologies. I thought you were aware.”

“Aware.”

“That Ishigami Senku enjoys spending time with you and wishes to do it more often. Unlike you, he is not so subtle in his desires.”

Gen giggles, trying to keep it from sounding too manic, and presses the dough back into shape. “Of course he enjoys my company, Francois-chan. I’m a treasure and we’ve been, dare I say it, friends for over a year now.”

“Asagiri-san, please don’t make me correct such a blatant attempt at falsehood.” Francois coolly sets their dough aside and powders the table with another pinch of flour. “You know as well as I that Ishigami Senku’s feelings for you exceed those of mere friendship.”

Before Gen can process _that_ , Chrome is running up, shouting something about pigs, and Gen can only go along helplessly.

So Francois, one of the smartest people on the planet, probably even without the petrification, seems to be laboring under the delusion that Senku has distinctive non-friendship feelings for Gen. How unfortunate. How...distracting.

Now his midnight ruminations have a whole new dimension to torture him with.

Senku is all over the place these days, in the air and on the water, back and forth between the village and the ship-building site, always doing and thinking about a million different things, and it’s not like Gen isn’t busy too, so the amount of time they spend together varies wildly. Now that he’s painfully aware of it (courtesy of Francois) Gen can’t ignore how Senku tries to stay nearby. If he has to switch locations, he comes up with a reason for Gen to come along, and if they have to act separately, Senku arranges frequent phone calls, ostensibly for management purposes. It’s definitely helpful to coordinate their movements, but Gen thinks they spend too much time snickering like schoolboys over the line for it to be completely professional.

“And what have we learned from this?” Gen asks, cheek propped on one hand.

“Don’t let Ryusui ride the minecart unsupervised,” comes Senku’s droll, tinny reply.

“Honestly, Senku-chan, that seems like common sense. I thought you were supposed to be a genius?” It’s way too late but Gen is still sitting on the floor of the observatory, listening to Senku recount an unfortunate incident at the mine, his face aching from smiling.

“I can’t be on all the time.”

“I guess that’s true. And Ryusui can be hard to handle.”

“You don’t seem to have a problem.”

“Oh my, Senku-chan, do I detect a note of bitterness?”

“The quality of this phone isn’t high enough for you to detect anything, mentalist.”

Gen laughs. “But I know you, Senku-chan.” _I know you_. _I’ve known you_. His smile freezes on his face.

“Unfortunately,” Senku sighs. “Though I’d prefer you didn’t.”

“Someone has to,” Gen forces out.

There’s a faint rustling on the other end of the line, like Senku shifting his weight. “Everything okay over there?”

“Of course, Senku-chan!” Gen says quickly. “Why wouldn’t it be?”

“You sound weird.”

“The quality of this phone isn’t high enough for you to—”

“Yeah, yeah—” a short burst of static, like Senku huffing out a laugh right into the mic. “Such a comedian.”

“I do my best.”

“Hey, uh—” Senku clears his throat and Gen tilts his head, listening intently. “I’ll be back in a few days.”

Gen’s stomach swoops involuntarily. “Okay? Everyone will be excited to see you.”

“You—” more shuffling. Gen pulls the earpiece back to raise an eyebrow at it. “Anyway—uh, it’s late.”

“Very observant, Senku-chan.”

“Go to sleep, mentalist,” Senku says shortly, and before Gen can respond, the line goes dead.

Gen squints at the blocky structure of the phone. What was all that about? With a sigh, he replaces the mic and the speaker in their cradles and pulls his blanket tighter around himself, turning his face into the starlight streaming in through the ceiling hatch.

He has a place to sleep in the village proper, but when he’s here, he prefers to stay in the observatory. It’s strange being here without Senku, but it’s also the place in the village that feels the most like him. Even the thought makes him feel like a pining maiden, but all his efforts to switch his emotions off have have come to naught, so he just buckles down and lets the inconvenient longing wash over him.

Above him, Sirius twinkles, a little out of place, and Gen wonders if Senku is looking at it too, so many miles away. It’s all so familiar. It’s all so new.

* * *

You up  
  
Yes, but I shouldn’t be. The grind never stops, it seems. Why are you awake at this ungodly hour?  
  
Got back late. Exploded  
  
What??  
  
What exploded?  
  
Sensei???  
  
Rocket  
  
You exploded a rocket?? A small one, right?  
  
Y  
  
Are you okay?  
  
Tired  
  
Ears hurt  
  
You should go to the hospital. What if you popped your eardrums?  
  
Already did. I’m fine  
  
Okay, that’s good. Go to bed then.  
  
Jeez, you really scared me.  
  
Sorry  
  
Wanted to text  
  
You  
  
I’m flattered, sensei. Please get some rest.  
  
Wish you were here  
  
Oh dear. You’re going to be so irritated in the morning.  
  
But as long as we’re being honest.  
  
I wish I was there too.  
  
Sensei?  
  
Are you asleep?  
  
Good night, sensei.  
  


* * *

When Senku does arrive a few days later, as promised, he apparently does so in the middle of the night and in complete silence because one minute Gen is fast asleep in the observatory and the next he’s blinking awake to a hand on his shoulder and a voice in his ear.

“Wake up, mentalist, we’ve gotta go.”

“Go—what—?” Gen pushes himself up, squinting through the half-light and catching the glint of Senku’s crooked smile. “Senku-chan?”

“Surprise.”

Gen runs a hand over his eyes. “Trying to sneak up on me?”

“Yeah, and it wasn’t easy.” Senku sits back on his heels, allowing Gen to push away the pile of blankets he’d amassed to ward off the encroaching chill of winter. “You weren’t in your hut. Why are you staying all the way out here?”

He’s too drowsy for this, Gen laments, reaching for his outermost robe to hide the blush warming his cheeks. “No reason in particular.” He shrugs the robe over his shoulders, pulling it close. “I like looking at the stars as much as the next guy, and sometimes I fall asleep.”

“Uh-huh.” The room is too dim for Gen to read Senku’s expression. “Well, come on, we’ve got places to be.”

“Places?”

Senku rises smoothly, offering a hand to help Gen up. “You’ll see.”

Stomach fluttering, Gen accepts and allows Senku to pull him to his feet.

A few minutes later, the fluttering turns to clenching.

“Senku-chan, you meanie! You tricked me!”

“How did I trick you?” Senku tugs on Gen’s arm but Gen plants his feet and refuses to move. “I never said _where_ we were going!”

“Don’t play that game with me! I’m the king of vague wording and you knew exactly what you were doing!”

“Turnabout is fair play, mentalist!” Senku gives another fruitless tug. “What, mad because I got one over on you?”

Gen glares. “Please, this hardly qualifies.”

“Then why are you so pissy?”

“Because—!” Gen gestures at the massive shape of the inflated hot air balloon tethered to the ground in front of them, so huge it blocks the view of the dark sky.

“You gotta go up at some point!”

“Why?” Gen demands.

“If nothing else, just to say you did.”

“I’m not nearly as vain as you seem to think I am.”

“I will carry you into that basket if I have to,” Senku warns.

Gen scoffs. “As if you could lift me.”

“I’m not strong but I can handle your scrawny ass.”

Gen turns his nose up haughtily. “Glass houses, Senku-chan.”

“Gen—“ Senku takes a step into him. “I want to show it to you.”

Gen blinks, taken aback, and Senku uses that moment of weakness to duck down and grab him around the waist.

“What—“ The world tilts violently and before Gen can react, he’s slung across Senku’s shoulders in a fireman’s carry. He flails against the hands gripping his arm and wrapped around his leg. “Senku-chan!”

“Give it up, mentalist,” Senku laughs, striding toward the the balloon without hesitation.

“This is kidnapping!”

“I’ll keep you safe, I promise.”

Defeated, Gen hangs morosely over Senku’s shoulders. He knows that if he pushed the issue, Senku would give up, but he also recognizes that Senku would have given up sooner if he didn’t have a good reason to keep trying. The act allows both of them to save face. So, benevolent ally that he is, he permits Senku to deposit him in the basket and only glares a little as Senku swings inside after him.

“Did you learn that from Kohaku-chan?” he asks snidely.

Senku sets about untying the tether ropes. “She said it was the only way I’d ever be able to lift anyone.”

“She’s probably right,” Gen mutters.

The basket lurches slightly as it loses contact with the ground and Gen grabs the edge in a white-knuckled grip.

“It’s alright,” Senku assures him. “I’ve got this. I do this all the time.”

“Yeah, with Ryusui-chan or Chrome-chan.” Gen watches nervously as Senku severs the last rope and turns to stoke the fire. “What good am I going to be when we’re about to crash and die?”

“I know how to handle it on my own now.” Senku grins. “And we won't be up for that long.”

“Ah, yes, that makes me feel better.” Gen watches the ground sink away from them and has to fight the urge to curl up in a ball.

“Just enjoy the ride, mentalist. Put it in your next book.”

“If you can believe this, I’m not getting a lot of writing done out here, Senku-chan.” The basket bobs past the tree tops and a wave of vertigo washes over him. “Maybe once we solve the grand mystery and save all of humanity, I’ll pen a bestseller about the Prometheus of the new world and how he forced me into a hot air balloon against my will.”

“Prometheus of the new world, huh?” Senku joins him at the edge of the basket, leaning way too casually against the wicker. “I kind of like that.”

“Did you miss the part about how I’m going to reveal all of your horrible antics?”

“Reveal away.” Senku waves a dismissive hand. “I’m not interested in being famous.”

“I’m afraid you won’t have much choice in that.” Gen presses his lips together and nervously eyes the rapidly shrinking forest of shadows below them. “How does anyone get used to this?” he mutters.

“Humans didn’t invent flight so they could stare at the ground,” Senku responds, his voice low and suddenly much closer than Gen was anticipating. A calloused hand cups his jaw and tilts his head up before Gen can resist. “Look up, mentalist.”

A glint of light, sudden and bright, makes Gen squeeze his eyes shut, and when he blinks them open again, he’s greeted by glowing pinks and oranges, early morning hues spilling over the clouds as the balloon rises through them. Gen sucks in an involuntary gasp, crisp air filling his lungs, transfixed by the riot of sunrise colors stretching before him. The sun is still just a glimmer along the horizon, but the rays catch in the dips and rises of the clouds surrounding them, casting the balloon into a sea of light.

It’s breathtaking.

A familiar clicking flash jolts Gen out of his stupor and he whirls around in time to see Senku lowering one of Minami’s boxy cameras and grinning impishly.

“Senku-chan, you _sneak_!” Gen shrieks. He lunges for the camera. “Give me that!”

Senku ducks out of the way, jumping to the other side of the basket, crowing with laughter. “Nope! You’re too late! I got the new world’s first paparazzi shot of celebrity psychic Asagiri Gen!”

“You’re gonna get my foot up your ass if you don’t give me that camera!”

“If you run around too much, you’ll tip the basket!”

Gen freezes instantly, grabbing the edge of the basket in terror.

“I’m kidding, I’m kidding!” Senku rounds the furnace, eyes wide, and puts a hand on Gen’s shoulder. “The counterweights will keep the basket still, and neither of us weigh enough to—”

Before he can finish, Gen snatches the camera out of his hand and leaps nimbly to the other side of the basket. He sticks his tongue out at Senku’s dumbfounded expression. “Don’t play with me, Senku-chan. You won’t win.”

Senku blinks and huffs out a breath, sticking his hands on his hips. “I guess not.”

Gen turns the camera over in his hands, frowning and fiddling with the little details. “It’s lighter than I thought it’d be.”

“It’s basically just wood and a mirror.” Senku creeps hesitantly to his side. “Nothing like the ones we’re used to.”

Gen examines the gears on the front of the camera. “I don’t think I’ve actually held one of these yet. Even though the whole thing was kind of my idea anyway.”

“You’ve pretty much avoided the cameras altogether.” Senku crosses his arms and leans back against the edge of the basket, watching Gen shrewdly. “Don’t think I haven’t noticed.”

“Oh, of course not.” Gen rolls his eyes. “Nothing gets past you, Senku-chan.”

“I would have thought celebrity psychic Asagiri Gen would be first in line for the limelight.”

Gen glances up at Senku, lips curling in a rueful smile. “Celebrity psychic Asagiri Gen doesn’t really exist anymore, Senku-chan. What good does the limelight do me now?”

Senku returns his gaze, eyes glittering, face dyed half-pink in the pastel sunrise. “You’ve got a good point. Our old selves...they vanished thousands of years ago. I guess none of those people really exist anymore.” He cocks his head. “Still, a shallow man like you doesn’t want to be in the history books?”

Tracing a nail over the smooth wood grain of the camera body, Gen looks back down into the lens, pursing his lips at the tiny, distorted version of himself reflected there. “I don’t really need people looking at me anymore,” he says thoughtfully. His former status has never really crossed his mind. Unlike Ryusui, eager to regain what he lost, and Francois, eager to return to the position they find most fitting, Gen has found himself content to use his skills for Senku’s benefit, furthering his plans. Before, he only sought notoriety because it was the best way to advance his craft while making a living. He enjoyed the attention, of course; he was young and cute, why wouldn’t he? But he never sought fame for fame’s sake. “I suppose I never really needed it,” he finishes quietly.

“Why go for it in the first place, then?”

“Sometimes life just take you where it takes you, Senku-chan,” Gen smiles. “Things happened, and suddenly I was in magazines and on TV. Don’t get me wrong—I liked it. I was being appreciated for my art, after all. But now—” Gen leans over to settle the bulky camera on the floor of the basket, careful despite his earlier protests. He doesn’t actually want to damage one of Senku’s survey instruments. When he straightens back up, Senku is eyeing him searchingly. “Now, _you_ appreciate my hard work, right, Senku-chan?”

One side of Senku’s mouth curls up in a slanted smirk. “Hell yeah.”

Gen claps his hands together. “Then that’s all I need!” Giggling, he turns to face the sky, bracing his forearms on the rim of the basket and leaning out enough to let the wind ruffle his hair. “I’m a bit different behind the cameras, anyway. Wouldn’t you agree?”

“I wasn’t a fan of yours or anything.” Senku scratches his cheek, shifting to face into the basket, one hand still resting on the edge, inches from Gen’s arm. “But I guess so. From what I saw, anyway. Always putting on a show.” He huffs out a breath. “Like how you used to be, when we first met.”

“What can I say? Old habits die hard.” Gen tilts his head back, enjoying the brisk air on his flushed skin. “We all act differently when we’re being watched, I suppose. There’s a scienc-y term for that, isn’t there?”

“In the broadest sense, yes, I guess that falls under the observer effect.”

A chill that has nothing to do with the cold runs up Gen’s spine. “Yes, I’ve heard of that one,” he says evenly, keeping his eyes fixed on the cloud-scudded sky in front of him. “It’s different from the uncertainty principle, right? You wrote them on separate cards in my deck.”

Senku lets out a quiet snort. “ _Of course_ they’re different. When you get down to it, they’re completely different phenomenons, so that confusion is mostly just ignorance.”

Gen hums absently, heart pounding. He could tip the scales right now. Spill everything.

Yuzuriha’s aggrieved face flashes across his mind.

_“That’s_ you _!”_

_“I don’t think it is anymore.”_

He’s not the person Senku texted accidentally. No matter what, he’ll never be him again. But—

_I guess none of those people really exist anymore_.

With Senku’s own words ringing in his ears, Gen throws caution to the winds whirling past their balloon. “You know, I never did find out what exactly Neils Bohr had to do with all that.”

“Oh, that’s easy—” Senku starts immediately, “—back when the theories were new, along with the entire concept of an observable quantum state, there was a lot of debate...about….” he trails off and Gen hears him inhale haltingly.

Fighting to keep his expression neutral, Gen pushes himself upright and turns to face Senku directly, finding him staring wide-eyed at the floor. “Go on, sensei,” he says softly. “I want to hear the rest.”

Slowly, Senku raises his head. “Is this a trick?” he asks, words so quiet they’re nearly snatched away by the wind.

“Do you really think I’d do something so cruel?” Gen shoots back.

“You—” Senku straightens up, one hand twitching abortively toward Gen. “You’re serious?”

“Ten billion percent!” Gen smiles brightly to hide the nervous twisting of his stomach. “Quite a coincidence, huh, Senku-chan?”

To his horror, Senku drops his head, pinching the bridge of his nose.

“I know this probably isn’t what you expected,” Gen babbles, trying to cover the terrifying silence. “Believe me, I was surprised too—I would have mentioned it earlier, but you have to agree it’s a bit of a strange topic—and I apologize if you’re disappointed, but—”

“Gen,” Senku rasps. “Just—be quiet for a second.”

Gen snaps his mouth shut so quickly his teeth click together.

Senku takes a few deep breaths. Tucking his hands into his sleeves anxiously, Gen watches Senku’s shoulders rise and fall, hardly daring to breathe himself. Then Senku’s shoulders stutter. Senku flattens both hands against his face and, actually, this is worse than the silence. Gen is seized with panic at the realization that he’s made the Prometheus of the new world cry.

“Senku-chan, I—”

“You absolute _bastard_ —” Senku jerks his head up, revealing a wide, toothy grin.

Gen blinks.

“Do you have _any_ idea how much I worried about you?” Senku demands. “I had no idea where to even look for you! I’ve been wracking my memory for clues, but that stupid rule we had—if only I’d been nosier, asked more questions—I thought I’d never see you again!”

Me—me too!” Gen lurches forward, propelled by the sudden swell of joy in his chest, and grabs Senku’s shoulders. “I thought I’d never—I mean we never even sent each other pictures, so how could we—I–I missed you so much!”

Senku grips Gen’s shoulders in response, still beaming. “I missed you too!”

A laugh, wild and ecstatic, tumbles out before Gen can stop it. “The stupidest thing is—you always reminded me so much of Sensei. I should have realized, I should have—“

Shaking his head, Senku tugs Gen in closer. “You seemed familiar too, and the way you talked, sometimes I could have _sworn,_ but the odds of that—“

“Astronomical,” Gen breathes.

“I wouldn’t believe it was possible if it wasn’t happening right now!”

“Sometimes—sometimes—“ Gen’s fingers curl into the material of Senku’s clothes, the soft hide bunching in his grasp, and meets Senku’s shining gaze with watering eyes. “Sometimes I could hardly stand it—you were _so like him_ , it almost hurt, like you were reminding me how much I screwed up—“

“We couldn’t have known—“

“Of course not, but—“ Gen searches Senku’s face, taking it in like it’s the first time all over again. The sharp brow, the thin lips, the shrewd eyes, the jagged scars—it’s all Senku, but now, for the first time since he found out, Gen finally accepts that it’s Sensei as well. “Senku-chan, I just—I missed you so much!” Eyes swimming with tears, he pulls Senku in, wrapping his arms around his neck in their second ever hug.

Senku responds instantly, embracing Gen tightly, and he’s so warm, hands like branding irons against Gen’s back. “I knew you,” he murmurs in Gen’s ear. “From the second I met you, I knew you. I always told myself it was impossible, that I was just deluding myself out of misery but—something inside me still knew.”

Gen chokes out a laugh. “That was your heart, Senku-chan!”

“Preposterous.” But when Senku leans back, his smile is the softest Gen has ever seen it. “Instinct, maybe. The odds that this would even happen—I still can’t wrap my head around it.”

“Fate,” Gen suggests.

“There’s no such thing as fate.”

“Regardless, I think you’re my fate, Senku-chan.” Gen places his hands on Senku’s cheeks, framing his face. “How else do you explain us meeting against all odds _twice_? Out of a whole world, you texted me, and out of a whole country, Tsukasa found me to track you down. There’s good luck and then there’s _destiny_.”

Senku rolls his eyes. “The circumstances are unbelievable, but to attribute them to concepts like fate and destiny is simply—“

Gen cuts him off by leaning forward and pressing their mouths together, trapping the rest of Senku’s words between their lips.

When he pulls back, Senku is staring at him, eyes wide and jaw slack.

“Only you could miss such an obvious romantic set-up, Senku-chan,” Gen smiles coyly. “It’s not every day a cute boy tells you you’re his destiny, you know.”

“You little—“ then there’s a hand on the back of his head and Senku is hauling him back in, sealing their mouths together again.

Gen didn’t wake up that morning expecting to be kissing Ishigami Senku in a hot air balloon before the sun was even completely up, but now that he’s here, hands fisted in Senku’s collar, pressed against Senku’s chest, completely protected from the chill by the heat growing between them—Gen can’t imagine being anywhere else.

“It’s always bothered me,” Gen says, a few hours later, watching Senku go through the process of developing the camera film in the lab. “Our last conversation.”

Senku hums, submerging the plate in a vat of some chemical. “What about it?”

“I didn’t get a chance to check my phone before I started my show.” Gen leans over the vat curiously. “And we were arguing. What did you send me?”

“Oh, right.” Senku sets his little tongs aside and turns to face Gen, propping one hip against the table. “Just something about your unsalvageable taste and the tragedy of modern science fiction.”

Gen laughs. “Yeah, I guessed as much.”

Senku reaches out, tracing his fingers down the opening in Gen’s robe. Gen watches raptly as he pinches the material, absently dragging his thumbnail over the edge. “It always bothered me too,” Senku confesses lowly. “Thinking that was the last thing I ever said to you.”

Heart thudding, Gen rests a hand on Senku’s wrist and steps into him. “Fortunately, you’ll have an infinite number of opportunities to berate me for my poor taste in the future.”

Senku flicks his eyes up to Gen’s, a smirk creeping across his face. “You’re right. I’ll get started on that right away.”

Gen giggles, pressing one sleeve to his mouth. “Please don’t hold back, sensei.” He starts, remembering. “Oh, that’s right. You must already know that I named your contact _Sensei_ in my phone, but what did you call me? Something cute, right?”

The hand on Gen’s robe stills. “Don’t get too excited, mentalist,” Senku says dryly. “I labelled your contact _machigatta bangō_.”

Gen blinks. “You...you called me _wrong number_?”

Senku shrugs. “It’s not like I knew your name.”

“So cold, Senku-chan!”

“I shortened it to Ma-ban after a while, and Taiju and Yuzuriha both called you Ma-ban-san.”

“That’s not much better!” Gen summons some tears and dabs at the corner of his eye. “I should have called you _science nerd_.”

Senku grins. “That doesn’t sound too bad.”

“I should have known you’d choose something boring,” Gen laments.

“Yeah, I’m really not sure why you’re so worked up.” Using his grip on Gen’s robe, Senku tugs him even closer, until Gen is practically in his lap. “Think about it this way: I talked about you so much, I had to give you a nickname.”

Gen pouts obstinately. “I’m still heartbroken.”

“That must be so hard for you.” Senku glances to the side. “Looks like the film is done.”

Reluctantly, Gen steps back and Senku fishes the plate out of the vat, shaking it a few times to flick the solution off.

“What do you think?” Senku asks as Gen peers over his shoulder.

Obviously, the quality can’t hold a candle to the cameras of the past, but it’s undeniably him, washed out by the sunlight and gaping like an idiot. “Destroy it.”

Senku laughs. “No way. This is a collector’s item.”

Gen rolls his eyes. “I thought you disliked sentiment.”

“It’s unproductive,” Senku agrees, setting the plate safely out of the way. “But this is different.”

“How so?”

Instead of responding, Senku snags Gen by the robe and hauls him in again.

“Honestly, Senku-chan, it’s not a handle—”

“I’ve thought about you everyday for thirty-seven hundred years,” Senku cuts in, eyes shining. “That’s brainpower I could have been using for something else. Now that I know where you are, my productivity is about to shoot through the roof.”

A smile unfolds inexorably across Gen’s face and he drapes his arms over Senku’s shoulders. “So utilitarian,” he chuckles, brushing their foreheads together. “But, really, this is exactly what I expected. I’m so flattered to be a waste of brainpower.”

“I can’t believe I didn’t realize who you were sooner,” Senku mutters. “It’s so obvious now. No one’s ever annoyed me like you do.”

Gen huffs. “Same here.”

Yuzuriha is going to be so happy, Gen thinks absently as Senku winds his arms around his waist and he slides one hand into Senku’s hair. And once she clues Taiju in, he’ll probably lose it. The villagers will be confused by the full story, but the modern folks will probably go nuts. Ryusui will be unbearably smug, and Francois will just smile mildly like always. Gen can’t help giggling against Senku’s mouth at the thought.

“What’s so funny?” Senku rumbles.

Gen’s smile grows. “Nothing. Just thinking about who’s responsible for all of this.”

Senku pulls back slightly to quirk an eyebrow at him. “And who would that be?”

Grinning now, Gen smooths Senku’s hair out of his face. “Bohr-chan, of course!”

Blinking, Senku smiles slowly in response. “Right. Thanks, Bohr.”

“Thanks, Bohr-chan!”

_Thank you,_ Gen thinks, laughing joyfully as Senku surges forward to catch the sound in his own mouth. _Thank you_.

**Notes for the Chapter:**

> i hope it was worth the wait lmao. let me know what you think! I'm busy with my other wips, but I love this pairing so much, there may be more sengen in the future if I can get my shit together.
> 
> follow me on [tumblr](https://mistresseast.tumblr.com/) and [twitter](https://twitter.com/MistressEast) for occasional sengen and constant nonsense!


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